Talk vs Walk - An introduction to the ethics of 1 John

Introduction

1 John 1 is a short chapter, only 10 verses, and serves as a two-part introduction to the rest of the letter. Verses 1-4 establish the theological trajectory of the letter. John opens the door to theological themes that he will explicate later, like the unity of essence between the Father and the Son, participation in the divine life according to union with Christ, the manifestation of life through the incarnation of Christ, and the hope of the resurrection, just to name 4.

Now, in verse 5-10, John opens the door to his ethical themes.

Primarily, John is concerned with the ethical implications of divine light for the life of the Christian, and how those ethical implications help us draw distinctions between professors of Christ and confessors of Christ, or, to put it differently, those who merely say they know Christ, and those who truly know Christ.

John is burdened in this letter to help his readers understand legitimate, authentic, real Christianity, both doctrinally and ethically, and he establishes many of his ethical themes here in these verses.

If we as students of the Scripture can get our minds thoroughly wrapped around verses 5-10, we will set ourselves up for success as we continue to study the ethics of 1 John.

With that in mind, let’s begin.

The Content of the Message

John jumps from verse 4 into verse 5 by defining his message. He danced around it in verses 1-4. He states the purpose for the giving of the message in verse 3 without actually telling us the true content of it. He simply says, we are declaring this message to you so that you may have fellowship with us, with the Father, and with the Son.

Now we have to get verse 3 right in order to understand verses 5-10. John is telling us that the message that he is declaring is one that is going to draw distinctions. It is a message that will separate the wheat from the tares and the sheep from the goats. The message he is proclaiming is what we might call a test of fellowship. In other words, he is writing to help his readers and us and churches throughout the centuries determine who is truly in fellowship with God and with Christ, and who is not.

This becomes the heart of 1 John, and John makes it abundantly clear: the distinguishing marks of a true Christian, the distinguishing marks of those who have true fellowship with the apostles, with the church at large, and ultimately with the triune God Himself, are clearly visible because they are ethical marks. They are behavioral. They concern that which is quickly and easily identifiable simply by looking at someone’s pattern of life.

And so John’s emphasis in these verses is on the distinctive categories that separate those who profess Christ in word only, and those who confess Christ by their actions and deeds.

The dividing line between these two groups is the message itself. And what is that message?

1 John 1:5 LSB

And this is the message we have heard from Him and declare to you, that God is Light, and in Him there is no darkness at all.

So what John is doing here then is anchoring his ethics in his theology. In other words, the Christian life in inextricably connected to what you know and affirm to be true about God.

There are some important things to be said here right off the bat, before even getting into the truth that God is light.

It’s important to realize that John, and indeed all the Biblical authors, attach their ethics to their theology, and they do in such a way that the two are inseparable.

Many Christians over the last 50 years or so have divested themselves of serious study of theology. They have done this intentionally, and in favor of a “practical” Christianity that “meets people where they’re at.” It’s a Christianity that’s primarily concerned with what a Christian is supposed to do rather than with who God is. Effectively what these professing Christians have done is removed God from the center of the Scriptures and placed man there. They go to the Bible for direction on how to live their life, rather than to encounter the thrice Holy God in the glory of His majesty.

But what John is saying here is that true Biblical ethics, true practical Christianity, cannot ever be separated or bifurcated from true Biblical doctrine, and more than that, your doctrine actually controls and compels your behavior.

For John, if a Christian is to walk in the light, he must first understand and affirm that God is light.

So for us, we need to remember that our practical concerns must be subservient and secondary to our doctrinal concerns. And the subtle miracle of this ordering of the emphases is that a Christian who is focused fully on the nature, character, and essence of God will inevitably demonstrate a thorough and robust commitment to the practical concerns of their day.

It has been famously advised, first by Oliver Wendell Holmes and then later by Johnny Cash, to not be so heavenly minded that you are no earthly good. Such advice is dangerous and unbiblical. Why? Because the Scriptures and the witness of church history is clear: those who are most heavenly minded demonstrate themselves to be of the most earthly good. C.S. Lewis said that a study of history will show you that those Christians who did the most for this present world were just those who thought most of the next. If we set our minds intently on the things above, we will find that we have a tempered and balanced motivation for the good of things below.

A word to us tonight then is this: if we want to be counted among those who walk in the light, we must be fervently committed to gazing upon the God who is light. Only when we are fully and completely absorbed in His light can we be equipped to walk in it.

So having said all that, let us now consider what it actually means for God to be light. This is a study unto itself, and indeed, the theme of God’s light has occupied theologians for decades and pages upon pages have been composed in devotion to unraveling all that is contained and implied by this phrase “God is light.” In fact, John Stott said that:

The Letters of John: An Introduction and Commentary 2. The Apostolic Message and Its Moral Implications (1:5–2:2)

Of the statements about the essential being of God, none is more comprehensive than God is light.

Therefore, we might rightly say that, if it were possible to summarize all that is in God with just a phrase, it would be this: God is light.

I want to make a few observations about this phrase here tonight.

John is making a statement about the simplicity of God. We have mentioned the doctrine of divine simplicity before. Simplicity essentially means that God not made up of parts that total a sum and make God who He is. He simply is. God Himself affirms and declares this to be true of Himself when He declares his name to Moses as “I am that I am.” God simply is. And so it follows that He simply is all of His attributes. Jesus says in John 4 that God is spirit. We hear in Isaiah that God is holy. John will tell us later in 1 John that He is love. And at this point, he tells us that God is light. There is much more to be said about simplicity, especially as it connects to God’s essential “lightness.” However, for now, we need to understand that for John to affirm that God is light, He is affirming that God is absolutely, unchangeable, and essentially light. God is the source and standard of light.

John is making a statement about the revelation of God. John Stott says this:

The Letters of John: An Introduction and Commentary 2. The Apostolic Message and Its Moral Implications (1:5–2:2)

It is his nature to reveal himself, as it is the property of light to shine; and the revelation is of perfect purity and unutterable majesty. We are to think of God as a personal being, infinite in all his perfections, transcendent, ‘the high and lofty One … he who lives for ever, whose name is holy’ (Isa. 57:15), yet who desires to be known and has revealed himself.

John tells us that God is light to demonstrate that we can know him. If something is shrouded in darkness and therefore invisible, we do not know that it exists. If we do not know that it exists, we cannot know anything else about it. Conversely, God is clothed in unapproachable light, is the source and creator of light, and is light in and of Himself. This means that God is not shrouded in darkness and can be known and is in fact known.

John is making a statement about the moral perfection of God. Again, John Stott:

The Letters of John: An Introduction and Commentary 2. The Apostolic Message and Its Moral Implications (1:5–2:2)

And if God is also light in the sense of possessing an absolute moral perfection, their claim to know him and have fellowship with him despite their indifference to morality is seen to be sheer nonsense, as the author goes on to demonstrate.

John tells us that God is light to demonstrate that He is perfect and holy. There are no shadows or dark areas with God. He is morally pure and holy.

Perhaps this concept can best be illustrated by taking a brief tour through the Bible and seeing how this concept of God as light is explained and illustrated.

We can begin in Genesis 1, where we see that the first thing God creates is light. T. Desmond Alexander connects this first act of creation to God’s revelation of Himself, as this light is called forth to banish confusion and establish order.

In Exodus, we, with Moses, encounter God in a burning bush that is described using words like bright and blazing. Again we see light being associated with revelation as God speaks to a man for the first time in 400 years.

Moving along, Israel is guided through the wilderness by a pillar of fire, the same type and category of fire as the bright and blazing bush of Exodus 3. We might rightly say that Israel was guided by a pillar of divine light. Again, the concept of guidance is connected with the concept of revelation. God reveals Himself in light.

Again in Exodus, we see that Moses beholds the backside of God during the receiving of the law, and it is here where we first begin to associate light with moral purity, for from the light comes forth the perfect law and precepts of God.

David and the rest of the psalmists speak regularly of God as light, and associate this light with revelation, moral purity, and truth. We recall the words of familiar Psalms: In your light we see light. Your word is a lamp to my feet and light to my path.

We then see this fulfilled both in word and in deed in the person of Jesus Christ. John declares Jesus to be the possessor of what we might call “life-light” in the prologue to his gospel, and then later in John 8 we hear Jesus say directly Himself that He is the Light of the world. So John finds, in Christ, the full and final fulfillment of the doctrine of divine light, and this is nowhere illustrated more plainly than in the transfiguration, in which the glory of Christ shines so brightly that the disciples are blinded momentarily. There Jesus is described as shining, white as light, and bright. Here then we see these themes of purity and truth come together as God commands the disciples to listen to Jesus as the disappearance of Moses and Elijah pictures Christ as the full and final revelation of God, fulfilling and completing the revelation given through the Law and the prophets.

Time forbids us from examining all the explanations of light in the New Testament epistles, but I do want to mention end of the book of Revelation, in which John describes the abolition of the sun because the Father and Son provide eternal light to the new heavens and the new earth. So we may rightly deduce that part of our hope of eternity is that we will bask forever in the light of God, and part of what makes heaven, heaven is the eternal and visible presence of that light.

So without going farther into it, though we certainly could, we can affirm with John that for God to be light is for Him to be truth and purity. In other words, God is the fountain, source, and measure of all knowledge, and he is the fountain, source, and measure of all morality.

Apart from God we have no standard of truth and apart from God we have no standard of moral behavior.

Robert Yarbrough summarizes the point nicely:

1–3 John Exegesis and Exposition

In view of OT precedent and Jesus’s usage, John’s reference to light in 1 John 1:5 may be taken to have programmatic significance for the epistle as a whole. It eventually becomes clear that the community he addresses is beset by darkness of a doctrinal, ethical, or relational nature, or some combination of the three. This marks a theological lapse—an inadequate response to God. Doctrinal error calls for corrective teaching, and John will offer it. Ethical negligence calls for fresh imperatives, and John will issue them. Relational breakdown (absence of compassion, presence of hate) calls for reinvigorated love for God and persons, and John will admonish readers in these directions.

But John’s frame of reference in the epistle is not dominated first of all by his teaching, his commands, or his encouragement to love, or even the occasions that call all these forth. It is dominated rather by his vision of God—God’s light, his moral excellence and efficacious purity. These render the error and confusion that his epistle addresses quite inappropriate and in fact eminently correctable. God’s light furnishes the standard and means by which John will be able to diagnose error and propound corrective measures. Because it is embodied in the crucified and risen Christ, it furnishes the transforming12 dynamic that makes truth and love possible for sinners in a world and local setting beset by deception and apparent animosity.

John’s message then is this: The truth and purity of God, as expressed in His fundamental and essential “lightness,” is the foundation for the doctrinal, ethical, and relational truth that I am writing to share with you.

So then, having considered the content of the message, let us now consider the implications of the message.

The implications of the message

This is where the rubber meets the road for John. He is concerned with false teachers and morally bankrupt leaders who talk a lot of talk.

Look at verses 6-10.

He puts forth three conditional statements based on empty words. If we say, if we say, if we say. He then contrasts the empty words with the righteous behavior of true light-walkers.

These statements follow a pattern: What someone says, what the implications of that statement are, what a light-walker does, and what actually happens to them.

Talk: Fellowship

John’s first polemic or attack is against those who say they have fellowship with God, yet walk in darkness. This is the age-old problem of the “professor.” They like to talk a big talk about their fellowship with God, but their walk, their life, their behavior simply does not match their words. They don’t put their money where their mouth is.

Now what does John mean by fellowship? John has in view the doctrine of union with Christ. Let’s allow John to explain himself:

John 15:1–11 LSB

“I am the true vine, and My Father is the vine-grower. “Every branch in Me that does not bear fruit, He takes away; and every branch that bears fruit, He cleans it so that it may bear more fruit. “You are already clean because of the word which I have spoken to you. “Abide in Me, and I in you. As the branch cannot bear fruit from itself unless it abides in the vine, so neither can you unless you abide in Me. “I am the vine, you are the branches; he who abides in Me and I in him, he bears much fruit, for apart from Me you can do nothing. “If anyone does not abide in Me, he is thrown away as a branch and dries up; and they gather them, and cast them into the fire and they are burned. “If you abide in Me, and My words abide in you, ask whatever you wish, and it will be done for you. “My Father is glorified by this, that you bear much fruit, and so prove to be My disciples. “Just as the Father has loved Me, I have also loved you; abide in My love. “If you keep My commandments, you will abide in My love; just as I have kept My Father’s commandments and abide in His love. “These things I have spoken to you so that My joy may be in you, and that your joy may be complete.

To have fellowship with God in Christ is to abide in Him as branches abide in the vine. To draw life and rest and joy and peace from the overflowing fountain of Christ’s life and rest and joy and peace. This fellowship is what Jesus prayed for:

John 17:20–26 LSB

“I do not ask on behalf of these alone, but for those also who believe in Me through their word; that they may all be one; even as You, Father, are in Me and I in You, that they also may be in Us, so that the world may believe that You sent Me. “The glory which You have given Me I have given to them, that they may be one, just as We are one; I in them and You in Me, that they may be perfected in unity, so that the world may know that You sent Me, and loved them, even as You have loved Me. “Father, I desire that they also, whom You have given Me, be with Me where I am, so that they may see My glory which You have given Me, for You loved Me before the foundation of the world. “O righteous Father, although the world has not known You, yet I have known You; and these have known that You sent Me; and I have made Your name known to them, and will make it known, so that the love with which You loved Me may be in them, and I in them.”

So let’s connect some ideas here by making some logical propositions.

Statement 1: God is light, truth, and purity, and in Him is no darkness, lies, or filth. Therefore, whoever or whatever is in Him, abiding in Him, and in fellowship with Him participates in light, truth, and purity, and cannot have any darkness, lies, or filth.

So, when someone claims to be in God, abiding in Him and in fellowship with Him, but does not participate actively in the light, truth, and purity of God, their actions deny the truth of their words.

No one can walk in darkness and also abide in God. It is a logical impossibility according to John, and indeed it is an ontological impossibility, for God’s very nature is light. Therefore, nothing can exist in Him that is non-light, and certainly nothing can exist in Him that is darkness.

So let’s summarize this: John is saying that walking in darkness is incompatible with fellowship with God, at the most basic ontological level. God’s very nature does not allow darkness near Him, let alone in Him.

Therefore John can conclude that the person who says they have fellowship with God but walks in darkness, lies and does not do the truth.

Colin Kruse points out that these false professors commit two sins:

The Pillar New Testament Commentary: The Letters of John (Second Edition) Claims to Know God Tested by Attitudes to Sin (1:5–2:2)

First, they are guilty of lying about their relationship with God. According to the message heard from Christ, God is light, and there is no fellowship between light and darkness, and therefore their claim to have fellowship with God (while walking in darkness) is false. Second, they are guilty of not doing the truth. The expression “do the truth” is found only here in 1 John, but occurs also in John 3:21 (“But whoever lives by the truth [lit. “does the truth,” poiōn tēn alētheian] comes into the light, so that it may be seen plainly that what they have done has been done in the sight of God”). In that context, “doing the truth” is the opposite of “doing evil” (John 3:20), which suggests that here in 1 John “doing the truth” means living in the light of the truth and seeking to avoid sin. It is not enough to claim to know God (as the secessionists did); people must also live in the light of that truth, putting it into practice and avoiding sin

And John Stott again:

The Letters of John: An Introduction and Commentary a. The Denial that Sin Breaks Our Fellowship with God (1:6–7)

We are right to be suspicious of those who claim a mystical intimacy with God and yet walk in the darkness of error and sin, paying no regard to the self-revelation of an all-holy God. Since God is light, such claims are ludicrous. Religion without morality is an illusion. Sin is always a barrier to fellowship with God

Let’s allow the apostle Paul to summarize for us:

2 Corinthians 6:14–16 LSB

Do not be unequally yoked with unbelievers; for what partnership have righteousness and lawlessness, or what fellowship has light with darkness? Or what harmony has Christ with Belial, or what has a believer in common with an unbeliever? Or what agreement has a sanctuary of God with idols? For we are a sanctuary of the living God; just as God said, “I WILL DWELL IN THEM AND WALK AMONG THEM; AND I WILL BE THEIR GOD, AND THEY SHALL BE MY PEOPLE.

Walk: In the light

John contrasts those who say they have fellowship with God but walk in darkness with those who walk in the light.

The command to walk in the light is found throughout the Scriptures.

Isaiah 2:5 LSB

Come, house of Jacob, and let us walk in the light of Yahweh.

Isaiah summons Israel to obedience by summoning them to walk in the light.

Romans 13:12 LSB

The night is almost gone, and the day is at hand. Therefore let us lay aside the deeds of darkness and put on the armor of light.

Paul urges the church in Rome to lay aside the deeds of darkness and put on the armor of light, implying that there is a protective dynamic to walking in the light, which might perhaps be illustrated for us by our natural tendency to want to walk, especially in Los Angeles, during the day time. Light is associated with safety and protection, while darkness is associated with danger and fear.

What’s interesting is that John gives us no real definition of walking in the light. He assumes that his readers already understand what walking in the light means. For the sake of clarity, however, let’s look at how John defines walking in the light in his gospel:

John 3:19–21 LSB

“And this is the judgment, that the Light has come into the world, and men loved the darkness rather than the Light, for their deeds were evil. “For everyone who does evil hates the Light, and does not come to the Light lest his deeds be exposed. “But he who practices the truth comes to the Light, so that his deeds may be manifested as having been done by God.”

The contrast then is this: one may say that they walk in the light, but what is truly telling is their actions: do they live in the light? Do they walk according to the truth? If not, we have no true reason to believe that they have fellowship with God and with us.

Now John qualified walking the light with two additional realities in verse 7:

We have fellowship with one another

This reality plays off of what John already said in verse 3 regarding his purpose for writing. John’s goal is koinonia, or Christian fellowship. John is therefore providing us with a basic test of fellowship. Walking in the light is a sign that one has fellowship with other light-walkers and by implication also has fellowship with the very God of that light. This has implications for the way we do church discipline. If someone makes a habit of walking in darkness rather than in light, we can deduce reasonably that we do not have true fellowship with this person because they do not walk in the light and therefore do not have fellowship with and abide in God. The result, ecclesiologically, is that they are to be removed from the visible fellowship of Christ’s church.

The blood of Christ cleanses us

John makes a second qualifier and one that is important for us to understand. He says that if we walk in the light, the blood of Christ cleanses us from sin. Now some people have interpreted this phrase causally, insisting that the blood of Christ cleanses us from sin because we walk in the light. This would make our justification to be caused by our own works, and we deny such a teaching. Rather what John is doing, and if you decide you want to parse out the Greek word there translated cleanse, you’ll see where I got this, what John is doing is demonstrating to us that these three truths, that we walk in the light, we have fellowship with one another, and we are cleansed from sin, are coequal and coexistent realities. You have to think of it like an if-then relationship rather than a causal relationship. If statement A (you walk in the light) is true, statements B and C (you have fellowship, you are cleansed) are also true. And you can swap out any of those statements and the proposition will always be true. If you are cleansed, you have fellowship and you walk. If you have fellowship, you walk and are cleansed.

A quick word on this idea of cleansing: it is the Greek root katharos which means pure. It’s used here in the present tense. So what John is telling us is that if we have fellowship with and abide in the light of God, our sins are perpetually being purified and cleansed by the blood of Jesus. In other words, Christ’s sacrifice is eternal, absolute, and utterly efficacious for His people. What this further means is that we are not only positionally pure, in other words, the red of our sin has been wiped from our ledger, but we are progressively pure, in other words, Christ’s mediatory work in heaven on our behalf and his sanctifying work in our lives right now through the ministry of the Holy Spirit are perpetually cleansing us from the power of sin.

So these three realities hang on each other in mutual dependence, and these three likewise differentiate the walkers from the talkers. The talkers say they know God, say they have forgiveness, say they have fellowship. The walkers, by their life, demonstrate outwardly the inward realities of light, fellowship, and forgiveness.

Talk: Sinless nature

John now addresses false teaching. The first contrast deals more with practical concerns, but this second one is theological while still being woven into practical reality.

John is addressing the notion that one can be sinless in their very nature, in other words, born without an inherent sin nature.

How can John know this for sure? How can he say with confidence that people in fact “have sin?”

Romans 5:19 LSB

For as through the one man’s disobedience the many were appointed sinners, even so through the obedience of the One the many will be appointed righteous.

Psalm 51:5 LSB

Behold, I was brought forth in iniquity, And in sin my mother conceived me.

John leans on Paul and David to prove that all of us “have sin.” Because of Adam, it is hardwired into us, passed on genetically from person to person throughout all of history. Only one person has ever been born without this hardwiring, and that’s because biologically he was not conceived of His earthly father, but was conceived of the Holy Spirit.

John anticipates some of the false teaching that has plagued the church over the centuries. This teaching became known as Pelagianism. We’ve discussed it before. Essentially Pelagianism teaches that all human beings are born morally neutral with no propensity to good or evil. Their own will and their surroundings and circumstances determine whether they will be a morally good or morally evil person. This teaching was condemned by Augustine of Hippo who wrote extensively on the Biblical basis for original sin, the human need for divine grace in salvation, and the glory of redemption in Christ.

Perhaps more familiar to us today, this same type of teaching was taken up and popularized in the early 20th century by Sigmund Freud, who I would argue has done more damage to the church in the last 100 years than almost anyone else. He too taught that humans were born morally neutral and that our circumstances and surroundings shape us into who we are and become morally. He took it step further and essentially removed all responsibility for immoral or evil actions from the person who perpetrated them and instead directed his students and clients to cast blame on parents, teachers, circumstances, or events.

This teaching was then “baptized” as it were, and introduced into the church through what has come to be known by it’s supporters as “integrative counseling,” and by it’s detractors, of whom I am one, Christianized psychology.

What this type of teaching attempts to do is sidestep the fundamental reality that all people are born sinners, haters of God, and in darkness. It removes the need for grace and forgiveness and replaces it with a need for new circumstances, new events, new friends, and new surroundings to make you feel better.

John can’t be more clear: this is a Satanic deception. A denial of original sin is self-deception, and indicates that the truth does not reside in you.

On the other side then, we must affirm original sin as Christians.

As the Heidelberg Catechism, Lord’s Day 3 teaches us:

Historic Creeds and Confessions Question 7

Question 7

Whence then proceeds this depravity of human nature?

From the fall and disobedience of our first parents, Adam and Eve, in Paradise; hence our nature is become so corrupt, that we are all conceived and born in sin.b

Question 8

Are we then so corrupt that we are wholly incapable of doing any good, and inclined to all wickedness?

Indeed we are; except we are regenerated by the Spirit of God.

What practical effects does this affirm have for the Christian? I can name at least three:

Affirming original sin gives us a more glorious view of the grace of God. God’s grace is not that great if we are born neutral, and are able to choose God at the Golden Corral buffet of worldviews and beliefs systems. But if we are born utterly incapable of true good, the grace of God that saves us out of that darkness becomes indescribably sweet and glorious and beautiful, and must prompt us to praise God all the more for His sovereign grace.

Affirming original sin helps us share the gospel. If God’s grace is not that great when you deny original sin, neither is the gospel that good of a message. Without original sin, evangelism becomes sales. But when you affirm original sin, you’re not a salesperson. You’re a foghorn on a Coast Guard ship in the middle of the night, proclaiming rescue to drowning sinners.

Affirming original sin helps us extend grace to others. If there’s no original sin, people are evil because they’ve decided to be evil. Affirming original sin reminds us that evil people, especially those who do not even profess to know Christ, are hardwired that way. They couldn’t stop their wickedness even if they tried. So we meet their evil with grace, overcoming evil with good, praying for their salvation, and reminding ourselves as Paul reminded the Ephesians, such were some of you.

Talk: Sinless life

Just as the false teachers were teaching that there was no original sin, so also they were teaching that there is no active or present sin. We see this in verse 10, so we’re going a little out of order here, but it’s connected to the previous point that John counters with his second walk statement.

John here affirms, in additional to original sin, that all people are likewise guilty of what we may call active sin.

Many people look at original sin as something that is somehow unfair. “How can I be held accountable for Adam’s sin?” John answers by saying, pointedly and simply, you’re being held accountable for your own sin. As soon as you take a conscious breath, from birth onward, you choose actively to sin. You commit sins against God and against neighbor as you act in accordance with your nature. John wants to be sure that there is no confusion: all people require forgiveness not only from their sinful nature but also from the individual sins that they commit themselves.

John is affirming this truth against those who would say that they’re basically a good person. Like Ray Comfort in a Way of the Master evangelism video, John is quickly and simply proving to his readers that all have sinned in darkness and fallen short of the light of God.

Walk: Confession

John contrasts saying that we have no sin, with confessing our sin. This will dovetail into his third point as well.

Now we said in verse 7 that walking in the light does not cause our cleansing in a positional or ontological sense. That sentiment holds true here.

We should parallel, as we did before, the three statements made here in verse 9. If you are habitually confessing your sins, you are continually being forgiven your sins and continually being cleansed. Again, as we said, if statement A is true, statements B and C are also true.

What John is telling us is that a principal part of walking in the light is a habit of confessing sin.

We might define confession, in this context, as bringing our sin out of the darkness and into the light, where the light of Christ can purge it and we can be forgiven and cleansed.

So if we are to walk in the light, we must bring our sin continually into that light so that it can be purged out of us and we can purified.

I can’t say this any better than John Stott, so listen to his comments on this verse:

The Letters of John: An Introduction and Commentary b. The Denial that Sin Exists in Our Nature (1:8–9)

The proper Christian attitude to sin is not to deny it but to admit it, and then to receive the forgiveness which God has made possible and promises to us. If we confess our sins, acknowledging before God that we are sinners not only by nature (sin) but by practice also (our sins), God will both forgive us our sins and purify us from all unrighteousness. In the first phrase sin is a debt which he remits and in the second a stain which he removes. In both he is said to be faithful and just. The first word may mean that he is faithful to his nature and character (cf. 2 Tim. 2:13). But the faithfulness of God in Scripture is constantly associated with his covenant promises (e.g. Ps. 89; Heb. 10:23). He is true to his word and faithful to his covenant. Since the new covenant includes the pledge, ‘I will forgive their wickedness and will remember their sins no more’ (Jer. 31:34), it is not difficult to see why God is said to be ‘faithful’ in forgiving our sins. But how can he also be described as just when he forgives us our sins? Some commentators relate God’s justice to his faithfulness and suggest that it is by being faithful to his promises that God is just to forgive. Even so it is a strange adjective to use. Justice is associated in our minds with punishment or acquittal, not with forgiveness. If God visits upon the sinner his sin and ‘does not leave the guilty unpunished’ (Exod. 34:7), how can he forgive sins? This is the divine dilemma. The Judge of all the earth cannot lightly remit sin. The cross is, in fact, the only moral ground on which he can forgive sin at all, for there the blood of Jesus his Son was shed that he might be ‘the atoning sacrifice for our sins’ (2:2). Cf. Romans 3:25, another passage in which the justice of God is related to the atoning sacrifice of Christ. So we may say that in forgiving our sins and cleansing us from them, God displays loyalty to his covenant—his faithfulness because of the word which initiated it and his justice because of the deed which ratified it. More simply, he is faithful to forgive because he has promised to do so, and just because his Son died for our sins.

God’s faithful and just forgiveness of sin is therefore the bridge between a God who is pure light and humans who are born in darkness.

Here then contains the very heart of the gospel for John: God is light, and in Him there is no darkness at all. We have darkness within us and do the deeds of darkness. How then can we walk in the light of God? By finding forgiveness and cleansing at the cross of Christ, where God’s faithful forgiveness and righteous wrath meet together as the Light of God bows His head in death.

If I might be so bold as to appropriate an ancient hymn, a modern musical, and a timeless allegory: at the cross, at the cross, at last I see the light, and the burden of my sin is lifted, rolling away into an empty grave, never to be seen again.

Plato said that the highest end of man was to exit the cave and enter into the light. What Plato missed is exactly how that happens. Instead of men exiting the cave and finding the light, the True Light came into the cave, and enlightens everyone, and He said this: I am the light of the world. He who follows me will never walk in darkness, but will have the light of life.

John’s ethic in this epistle is a gospel ethic. It is an ethic that acknowledges God as light, truth, and purity, and as the only standard for moral excellence. It is an ethic that acknowledges our sinfulness, both in our natures and in our actions. And most importantly, it is an ethic that is practical and attainable for all people because, by the cleansing power of Christ’s blood, the darkness can be purged, the light can enter in, and we can have fellowship with God Himself, light with light, according to the light of Christ that has shone in our hearts.

That’s the foundation for John’s ethics.