Trinity “Son” Day

Big Idea - United in Christ as sons of God by faith

Through faith in Jesus Christ—the true Son and promised Seed of Abraham—believers are united with Him and therefore become God’s sons and heirs, sharing together in His promise and inheritance.

(In Christ, believers share in the promise and inheritance as sons of God by faith.)

Opening Illustration - How one joins a family

In the modern world, there are three ways that I can think of through which one joins a family. First, and most obviously, one is born into a family by nature. Second, one can be adopted into a family by volition and affirmed by a legal court. Third, one can marry into a family.

Interestingly, through union with Jesus Christ, the second two options are realities for us as believers. The third option of marriage is not addressed in today’s passage but it is true. The Church is the bride of Christ and as members of the church by faith, we, the Church, are one with Jesus Christ as the bride of Christ.

But for today’s attention, we are looking at this second option, adoption. Believers are received into the family of God as Sons of God because God chose us. God freely chose to adopt those united in Christ to be His children, to have the rights of sons, and to be in intimate fellowship with Himself as Father. As sons of God, we have been adopted as his children!

The Law was temporary Guardian

Galatians 3:23–25 ESV

Now before faith came, we were held captive under the law, imprisoned until the coming faith would be revealed. So then, the law was our guardian until Christ came, in order that we might be justified by faith. But now that faith has come, we are no longer under a guardian,

Reminder of last week - the law increases transgressions and condemns

We concluded our section last week with Paul’s analogy of the law as a prison. The Jewish people thought of the law as a fence that guarded and protected them, but in reality the law was a prison fence that confined and condemned them. The law could not justify the people of Israel, it could only diagnose the problem of sin.

From prison to guardian

Paul shifts his analogy from the language of prison to that of a guardian. The word guardian here needs a little explanation since it is foreign to our modern context. The guardian was generally a slave who was appointed over the children of their master to supervise, discipline, and train the children. So in this case, the child, being a minor is found to be under an authority that is temporary and serves a purpose, and that purpose is to guard and train the child in preparation for the time that they come of age to receive their inheritance or responsibilities of adulthood.

Christ marks the arrival of the age of fulfilment

Jesus Christ is the fulfillment of the promise to Abraham. In other words, the object of faith pointed to throughout the Old Testament covenants has now been revealed in the person of Jesus Christ!

The promise that the Old Testament saints looked forward to has now been revealed!

And now that Jesus Christ has come, the law’s purpose has been fulfilled. The law no longer serves the purpose of a guardian to point one back to the promise because the promise has arrived with the freedom of Jesus Christ!

Union with Christ makes one an heir of the promise

Galatians 3:26–29 ESV

for in Christ Jesus you are all sons of God, through faith. For as many of you as were baptized into Christ have put on Christ. There is neither Jew nor Greek, there is neither slave nor free, there is no male and female, for you are all one in Christ Jesus. And if you are Christ’s, then you are Abraham’s offspring, heirs according to promise.

We are Sons of God by faith alone

Justification comes by grace alone through faith alone in Christ alone.

We are declared righteous in Christ. We stand in the righteousness of Christ! Not through keeping the law. Not by our ethnic identities, but through union with Christ!

We have been baptized into Christ

This is a big deal. We have been baptized into Christ.

Romans 6:4–6 ESV

We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life. For if we have been united with him in a death like his, we shall certainly be united with him in a resurrection like his. We know that our old self was crucified with him in order that the body of sin might be brought to nothing, so that we would no longer be enslaved to sin.

Baptism is no mere ritual. Baptism is a holy mystery through which the grace of God is applied and one is initiated into the covenant family of God. Baptism is not only an individualist or personal response of faith, but it is the corporate initiation into the body of Christ by grace alone. Whether you were baptized as an adult or as an infant, the washing of water that was applied reflects the washing of grace applied by the power of the Holy Spirit.

Not only are we baptized into Christ, but Paul continues that this unity with Christ through baptism results in taking off the clothes of the old self and putting on the clothes of Christ, echoing Ephesians:

Ephesians 4:21–24 ESV

assuming that you have heard about him and were taught in him, as the truth is in Jesus, to put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires, and to be renewed in the spirit of your minds, and to put on the new self, created after the likeness of God in true righteousness and holiness.

In baptism, we are initiated into Christ by dying with him, by being washed of the old self, and invited into union with Christ.

Through union with Christ by faith we receive the righteousness of Christ, the sanctification of the Holy Spirit, adoption as sons of God and heirs of the inheritance, which is eternal life. Because we are united to the true offspring of Abraham, we share in His inheritance!

Equal Standing before God in salvation

Union with Christ reveals the equality of all before God in salvation. In other words, there is no class system in salvation. It doesn’t matter if you are a Jew or Greek, slave or free, male or female, white or black, and so on. There is equal access in Christ Jesus to salvation, and there is equal standing before the Father in Christ!

Paul does not mean that these distinctions no longer exist. Men are still men, women are still women (Eph 5:22-23). Jews and Gentiles still have an ethnic distinction. Masters and servants still maintain distinct callings within their first century world (Eph 6:5-9).

Paul here removes every barrier to salvation and inheritance in Christ, but this does not erase God’s created distinctions. All Image-bearers stand before God in Christ equal in dignity, equal in salvation, equal in inheritance, yet still distinct within God’s wise design. We must be careful to not move beyond what Paul is saying here.

Before we get distracted by one of the most contentious verses in the modern, Western Church, let’s return to Paul’s main point in this section of Galatians:

Christ is the true offspring of Abraham

The promise to Abraham in Genesis 12 and the covenant to confirm the promise in Genesis 15 culminate and are fulfilled in Jesus Christ, and believers inherit the promise through him and him alone. We are baptized into Christ, and receive the promise in Christ!

In the Fullness of Time God adopted us as Sons

Galatians 4:1–7 ESV

I mean that the heir, as long as he is a child, is no different from a slave, though he is the owner of everything, but he is under guardians and managers until the date set by his father. In the same way we also, when we were children, were enslaved to the elementary principles of the world. But when the fullness of time had come, God sent forth his Son, born of woman, born under the law, to redeem those who were under the law, so that we might receive adoption as sons. And because you are sons, God has sent the Spirit of his Son into our hearts, crying, “Abba! Father!” So you are no longer a slave, but a son, and if a son, then an heir through God.

Back to the slave/heir analogy

The child, even while under the management of a guardian is truly an heir, even before they have the freedom of adulthood. Israel, as the people of God under the law was truly God’s covenant people, yet they grew up as children under restraint until the promise came to fulfillment.

Slaves to the elementary principles of the world

Let’s take a moment to address this odd phrase. What are the elementary principles of the world?

The Greek literature in Paul’s day that we are aware uses this phrase to refer to the four elements of the material universe - earth, wind, water, and fire. A plain reading of this text, meaning that we try to understand it in a commonsense interpretation of the first century greek Christian, would result in this understanding. But what does that mean?

For the Jewish Christian, we have good reason to interpret it as the law of Moses as the elementary principles of the world under which they were in bondage, but for the Greek Christian, it likely refers to the natural law and to idolatry. The non-Jewish believers, before Christ came were enslaved to sin through the law that God has placed over all creation through the conscience and common grace, as well as the law imposed through their false gods who come out of the worship of these elementary principles. This idea is supported by Paul’s further explanation in Galatians 4:8–9 “Formerly, when you did not know God, you were enslaved to those that by nature are not gods. But now that you have come to know God, or rather to be known by God, how can you turn back again to the weak and worthless elementary principles of the world, whose slaves you want to be once more?”

In other words, these elementary principles of the world are the lesser forces or lesser “gods” which take the place of the true and only God in the hearts and minds of those who do not know God by faith through Jesus Christ. These lesser deities enslaved in the same way that the law enslaved. But God came himself to set things right.

The fulfillment was the Son sent by the Father

Jesus Christ, the Son of God came born of a woman and born under the law. What Paul is communicating is that Jesus Christ was truly man and truly subject to the full law of God given to the Jewish peoples.

Being true God and true man, Jesus Christ lived a live like you and I, yet he lived it without sin. Jesus Christ lived a righteous life, yet he became a curse for you and I. He bore the full curse of the law that He did not break so that those who believe in Him may bear the full righteousness of Christ, which we could not live.

Adoption through Christ

John Calvin wrote that “Christ became Son by nature so that we might become sons by grace.”

Here we see a shift from the forensic meaning of justification to the relational meaning of adoption. Up until this point, Paul has been speaking directly to justification.

Justification

Let me try to explain justification simply.

God is perfectly holy and perfectly just. He is the righteous Judge of all the earth, and He always judges rightly.

We, however, are sinners. We have broken God’s law in thought, word, and deed. We are not merely imperfect—we are truly guilty before a holy God.

Because God is just, He cannot simply overlook sin or pretend guilt is innocence. A corrupt judge excuses evil and calls the guilty righteous. But God is not corrupt. He does not lie. He does not bend justice.

So how can guilty sinners be declared righteous without God compromising His justice?

God the Son willingly came in the flesh. Jesus Christ lived the life we failed to live—perfectly righteous, perfectly obedient, without sin. Then at the cross He stood in the place of sinners and bore the penalty we deserved. The curse of the law that belonged to us was laid upon Him.

He took our place.

He bore the penalty our sin deserved.

And because Christ fully satisfied divine justice, God can now justly forgive sinners who trust in Christ.

Our sin is counted to Christ.

He bears our guilt and condemnation.

Christ’s righteousness is counted to us.

We receive His perfect standing before the Father.

So justification means that God, the righteous Judge, declares the believing sinner righteous—not because we have become righteous in ourselves, and not because God ignored our sin—but because Jesus Christ has paid our debt in full and His righteousness has been credited to us.

So at the cross, God remains perfectly just.

And through Christ, God becomes the justifier of the one who has faith.

As Paul says in Romans 3:26 “so that he might be just and the justifier of the one who has faith in Jesus.”

Adoption

I’ve said a lot about justification to make this point about adoption. It is far to easy within our reformed tradition to stop at justification by faith alone and then move on from Galatians, but the flip side of this beautiful coin of salvation is adoption.

Because the Gospel does not end with a courtroom verdict. Yes, God is the Judge, but God is also the Father, and the story of the Gospel does not end with a verdict of “forgiven in Christ” and “not guilty.” The Gospel continues with being received into God’s family as Sons of God. If Christ’s righteousness becomes ours through justification, Christ’s inheritance becomes ours through adoption!

In Jesus Christ, the Father calls you sons! And I want to take a moment to highlight the significance of what it means to be sons instead of sons and daughters as some translations put it. In the 1st century, the normal practice was for sons to receive an inheritance, while generally daughters did not. Paul refers to all who participate in union with Christ to be sons of God, pointing back to Galatians 3:28 “There is neither Jew nor Greek, there is neither slave nor free, there is no male and female, for you are all one in Christ Jesus.”

In Christ Jesus, you are sons of God, and heirs of the promise.

God as Judge has acquitted us through Christ.

God as Father has embraced us in Christ.

and God the Spirit has assured us!

Assurance of the Holy Spirit

The Holy Spirit, who comes from the Father and through the Son was sent by the Father and the Son to apply redemption into our hearts and seals our adoption as sons of God that we may cry out to our God personally and intimately. As a child cries out “daddy” or “dada” we may cry out “Abba Father” through the indwelling of the Holy Spirit who is the assurance of our salvation!

Trinity Sunday

How wonderful a text for this specific church holiday. We see in the text today that the salvation is distinctly Trinitarian. We are justified in the Son, adopted by the Father, and assured through the Holy Spirit.

Wrapping up, we saw that under the law, we were imprisoned, guarded, and awaiting the promise, but in Christ the promise is fulfilled, and we are justified, united in Christ, and adopted by faith, and we are filled with the Holy Spirit as heirs to the promise and assured of our salvation.

With this assurance, let us not return to our former bondage, but let’s seek to know the Father personally and intimately for His glory and our satisfaction.

Stand in the love of the Father, because you have been purchased by the blood of Christ, and have been confirmed, authenticated, and ratified by the Holy Spirit as a son.