Kingdom Sincerity: Christ's Call to Radical Truthfulness | The Book of Matthew: Sermon on the Mount | Matthew 5:33-37 | John Lee

Good morning! My name is John Lee and I serve Mission Church as one of the pastors. I am honored and excited to be with you this morning!

Our mission and vision is to partner with God to see His Kingdom come here in Las Vegas as it is in Heaven. And we believe that the best way of accomplishing our mission is by loving Jesus…by pursuing a life that lives like Jesus...... and by intentionally leading others to know and to love Jesus.

We have been in a sermon series through the Gospel according to Matthew and this morning we find ourselves in the midst of Christ’s Sermon on the Mount…which just so happens to be the greatest sermon ever preached by the greatest preacher who ever lived. And....over the past several weeks we have been working from a thesis found in Matthew 5:20.

Matthew 5:20 (CSB)

20 For I tell you, unless your righteousness surpasses that of the scribes and Pharisees, you will never get into the kingdom of heaven.

Over the past several weeks we've seen Jesus analyze different parts of God's moral law....and so far....Jesus has pointed out the misuses of the sixth Commandment, “You shall not murder” and the seventh Commandment, "You shall not commit adultery.” Jesus also pointed out how the teachers of the Law were twisting and misusing God’s instructions regarding marriage and divorce.

And.....now…this morning..... we continue this same pattern as our passage provides us with the fourth of six illustrations that Jesus used to depict a “righteousness [that] surpasses that of the Scribes and Pharisees”....and this fourth illustration addresses the ninth commandment which says,

Exodus 20:16 (CSB)

16 Do not give false testimony against your neighbor.

And....Jesus....He addresses this commandment because…well....just like the laws on murder and adultery....the religious leaders were twisting and misusing God’s teaching on oaths and vows......and so.....Jesus takes some time to help us understand God’s true intentions of the ninth commandment and he calls us to pursue a life of righteousness that clearly surpasses that of the Scribes and Pharisees.

So...... with this all in mind …I want invite you to turn in your Bible to Matthew 5:33-37…and when you’re there and if you are able to…please stand for the reading of God’s holy and inspired Word.

Matthew 5:33–37 (CSB)

33 “Again, you have heard that it was said to our ancestors, You must not break your oath, but you must keep your oaths to the Lord. 34 But I tell you, don’t take an oath at all: either by heaven, because it is God’s throne; 35 or by the earth, because it is his footstool; or by Jerusalem, because it is the city of the great King. 36 Do not swear by your head, because you cannot make a single hair white or black. 37 But let your ‘yes’ mean ‘yes,’ and your ‘no’ mean ‘no.’ Anything more than this is from the evil one.

This is the Word of the Lord

Let’s pray

We live in a culture where the truth is relative and the result is a world that is saturated with deception and dishonesty. There is an overwhelming and pervasive indifference to truth-telling, and this has not only infected our day to day conversation but has invaded the most solemn pledges of life. Perjury under solemn oath is expected and the sacred vows of marriage are broken almost as fast as they are made. God’s name is invoked by blatant liars who claim to be witnesses of the truth. It seems that trust is hard to come by because truth seems to evade us.

All you have to do is turn on the news and scroll through social media to see that there is an actively eroding trust, a fostering of disunity, and a weakening of the fabric of our relationships and society. So tell me...... In this world where falsehoods are the common dialect, how do we know who or what we can trust?

There is, indeed, a crisis, but it's crucial to acknowledge that it's not isolated to external factors but it also permeates our own community. I mean.....it’s difficult to always tell the truth…for .....all of us have an inherent tendency to deceive and manipulate. Think about it........How often do we say things that we don't entirely mean? How often do we find ways to slowly backpedal our way out of agreements? We clearly agree to do something and then we find little loopholes that allow us to get out of what we said we would do. We are so quick to demand the truth of others and to condemn others when they don't live up to the standard of truth...and....We are simultaneously just as quick to just whitewash over all of the areas where we don't live according to the truth.

Our tongues are guilty of false witness, lying, gossip, slander, boasting, flattery, and cursing. We bend the truth to earn the approval of others....we lie in order to manage or manipulate other's emotions. We use filters on our social media pictures and die our hair ...we even lie about our weight on our drivers license.

The great preacher and author George Macdonald wrote to his son on December 6, 1878,

“I always try—I think I do—to be truthful. All the same I tell a great many lies.”

I don’t know about you....but I identify with Macdonald. There are times I am speaking with someone and I suddenly realize that what I am saying is not the truth. Maybe you have experienced the same thing? And I think this difficulty comes from a mixture of my own deceitful nature and the pervasive deceptiveness of our culture. And a result.....I cant help but wonder......as we live in this world of deception and among a people whose nature is inherently deceitful...... is it possible for us to rise above this prevailing culture of dishonesty? Is it possible for us to live an authentic, genuine, and trustworthy life in the midst of this muck of deception? How can we tell the truth in a truth-perverting world?

Well....our text this morning gives us hope.......you see......it is because God kept His Word and sent Jesus to fulfill His promises and to die for our false lie-telling......that we can be transformed by the grace of God to be a people of sincerity and truth as we build a community defined by radical truthfulness! And we are going to see this in our text in three movements

1. God's Command (v. 33-34a)

2. Jesus' Exposition of God’s Command (vs. 34b-36)

3. Christ's Call to Sincerity: Living Truthfully in a Deceptive World (v. 37)

1. God's Command (v. 33)

Matthew 5:33 (CSB)

33 “Again, you have heard that it was said to our ancestors, You must not break your oath, but you must keep your oaths to the Lord.

Here in verse 33..... Jesus summarizes not only the ninth commandment, which instructs against lying, but also the entirety of the Old Testament’s teachings on oaths and vows. But... before we dive into what it is Jesus is teaching .....we first need to understand what in the world we’re talking about here.........In other words........What exactly are oaths and vows?

Well.......when we talk about oaths we’re referencing a practice similar to when individuals are sworn in to testify in a court of law...... and an oath usually invokes some sort of sacred object in order to strengthen someone’s statement or promise.…think about someone putting their hand on a Bible as they are being sworn in to give a testimony and you get the idea.

Vows…like oaths involve invoking God's name to strengthen a promise…but unlike an oath…a vow is a promise made directly to God Himself. Think about a man and a woman on their wedding day standing before each other.....and promising God that they will fulfill their duty as a husband and a wife…and you get the idea.

Now....as we consider God’s command regarding oaths and vows its important to note that vows and oaths were encouraged…and not only were they encouraged but God encouraged us to make them in his name!!

Consider Deuteronomy 10:20

Deuteronomy 10:20 (CSB)

20 You are to fear the Lord your God and worship him. Remain faithful to him and take oaths in his name.

You see.....this practice of making an oath or a vow in God’s name was not only presumed but it was encouraged. However....making a vow and promising something in the name of the Lord was not to be taken lightly.......in other words..... if you weren't planning on following through with it then you better think twice about making a vow. In fact…Moses emphasized this in Leviticus 19:12.

Leviticus 19:12 (CSB)

12 Do not swear falsely by my name, profaning the name of your God; I am the Lord.

and also in Numbers 30:2.

Numbers 30:2 (CSB)

2 When a man makes a vow to the Lord or swears an oath to put himself under an obligation, he must not break his word; he must do whatever he has promised.

In other words....oaths and vows are serious business! In fact.......there is absolutely no circumstance that should lead you to breaking your oath or vow…however.... this does not mean that we shouldn’t swear an oath or make a vow at all.

You see..... It’s important to note that .....the Bible is not forbidding them…in fact.........God himself swears oaths! Consider how....in the book of Genesis .....God swears to Abraham that He would send a redeemer (Luke 1:68, 73) and later in Genesis 9 God swears that He will never send another universal flood…and in Psalm 16 …God vows that He will raise His redeemer from the dead.

Even the Apostle Paul regularly swore by God’s name. In fact .....he calls God as his witness several times throughout his letters......consider Romans 1:9.

Romans 1:9 (CSB)

9 God is my witness....

consider also

2 Corinthians 1:23 (CSB)

23 I call on God as a witness, on my life, that it was to spare you that I did not come to Corinth.

You see....the Bible is not forbidding you and I to swear an oath or to make a vow.....on the contrary!…It actually encourages us to do so....for they are designed to encourage truthfulness......which is also why the Bible also clearly forbids us to make false promises....or irreverent oaths.....in fact....doing so would be to break the third commandment which says

Exodus 20:7 (CSB)

7 Do not misuse the name of the Lord your God, because the Lord will not leave anyone unpunished who misuses his name.

Making a vow or an oath in the name of the Lord and breaking it is a part of what it means to take Lord’s name in vain. So again....you can make a vow…you can swear an oath by Gods name.....just make sure you keep it…because if you don’t....well....you are guilty of breaking not only the 9th commandment but also the third.....which is intense for we know that to disobey just one of God’s Commands is equal to disobeying all of them!! And....the truth is friends....we are all guilty.....we have all broken our promises! We have all gone against our word! We have all lied......and found loopholes to get out of doing what we have said we would do.

And …this leads us to a conundrum.......If the Old Testament did not forbid the making of oaths and vows....and even encouraged the swearing of vows in the name of the Lord....then why does Jesus say what He says in verse 34 ?!?!? why does Jesus say.....

Matthew 5:34 (CSB)

34 But I tell you, don’t take an oath at all...

At first read....... it seems as though Jesus is changing the Law and making it easier for us to obey it..... I mean…think about it.....if we’re guilty of breaking our oaths…and of not keeping our vows…..and as a result...... we are now guilty of using the Lord’s name in vein and bearing false witness ......then ..... well..... why not create a new law that will prevent us from disobeying?

Is that what Jesus is doing? Is jesus changing the law to make it easier for us obey it???

Well.... some denominations that would say …yes. In fact …this text has led many Christians to believe that Jesus is prohibiting us from taking oaths in a courtroom......or from taking an oath of allegiance to serve in the military or in law enforcement....some have even applied this to a refusal of taking wedding vows! But I submit to you this morning that…well…they have missed the plot …these folks have not fully understood what Jesus is saying....which leads us to the texts second movement.

2. Jesus' Exposition of God’s Command (vs. 34b-36)

Let’s revisit verse 34:

Matthew 5:34 (CSB)

34 But I tell you, don’t take an oath at all...

So, why does Jesus seem to be altering the Law? Well, he isn’t fundamentally changing it; instead, he's tackling the pervasive issue of lying from a different angle. It’s crucial to understand that the people listening to Jesus had been taught a distorted version of God’s Law. Over time, the Pharisees and the teachers of the Law had twisted the original teachings. They propagated a dangerous idea that an oath or vow was only binding if it included God’s name. In other words, if you made a promise or swore an oath by your own name or someone else’s life, you were not obligated to keep it. This misinterpretation led to an intricate web of rules, creating convenient loopholes for dishonesty.

Consequently, a rampant epidemic of frivolous swearing took hold. Oaths and vows were made without any intention of fulfillment. Phrases like “By your life,” or “by my beard,” or “may I never see the comfort of Israel if…” became commonplace. Everyday language, meant to convey truth, became saturated with deception and manipulation. It wasn’t just the act of lying; it was a subtle, crafty trickery, convincing others of one’s honesty while concealing falsehood.

Imagine a child eagerly promising to share their favorite toy with a friend. Yet, secretly, behind their back, they slyly cross their fingers—a cunning loophole to evade their commitment. This seemingly innocent gesture hides profound deceit, enabling them to momentarily please their friend while freeing themselves from their obligation. It’s a subtle maneuver, a way of saying, “I have my fingers crossed, so I don’t have to tell the truth.” And this childish behavior mirrors the intricate system of loopholes that had infiltrated the practice of making oaths and vows, which is precisely what Jesus is warning against. Jesus is addressing this deceptive manipulation of words. Let’s refer back to Matthew 5:34-35.

Matthew 5:34–35 (CSB)

34 But I tell you, don’t take an oath at all: either by heaven, because it is God’s throne; 35 or by the earth, because it is his footstool; or by Jerusalem, because it is the city of the great King.

Remember, the teachers of the Law were saying, “Your vow is only binding if you swear by the name of the Lord… if you swear by anything else and lie… well… you’re just fine. You do not have to worry about disobeying God.” And Jesus says, “What? It doesn’t matter who or what you swear by. If you do not keep your word, you are in violation; you are in direct disobedience of the ninth commandment: ‘You shall not bear false witness.’”

Jesus is also emphasizing that swearing by things like heaven, earth, or Jerusalem is a violation of the third commandment: "You shall not take the name of the Lord your God in vain." This commandment is significant because heaven, earth, and Jerusalem are places where God has placed His name. He created the heavens and the earth to magnify His glory; they belong to the Lord entirely. Jerusalem, too, was a place where God chose to reveal His presence. These locations were intended to showcase God's majesty. So, by swearing by these places and then failing to keep your oath, you're treating the Lord's name as something trivial and insignificant. It's not enough merely to avoid explicitly invoking the name of the Lord; swearing by heaven, earth, or Jerusalem still disrespects the glory these places were designed to reflect.

I am reminded of the Westminster Shorter Catechism 55, which says,

"The third commandment forbids all profane thing or abusing anything whereby God makes Himself known." - Westminster Shorter Catechism 55

It’s not only about refraining from using the Lord's name as a profanity. That’s a part of it, yes and amen. But Jesus is also emphasizing here that using these things as part of your oaths and then breaking those oaths is problematic. What Jesus is highlighting is not just a matter of honesty but also how you construct these oaths. If you structure them in a way that allows you to find loopholes to evade keeping your word, it reveals an issue within your heart—a lack of integrity and a low regard for God and His name.

Let’s be real. This lack of integrity and the pervasiveness of dishonesty begin to show their ugly head extremely early in life! Just the other day, I came downstairs to find cupcake sprinkles, chocolate chips, and marshmallows all over the kitchen. Someone had gotten into my wife’s baking cabinet. So, the investigation began. Who in the world could it have been? It wasn’t long before my dear Juniper lackadaisically wandered into the kitchen with chocolate all over her face. And she pretended to not see the mess. “Sweetheart, do you know what happened in here? Why are mommy’s baking supplies all over the kitchen?” And confidently she replied, “I have no idea, Daddy!” Sure!!!

And here’s what happens. Kids, including me and including you, as we grow up, we get better at lying. We learn what we can lie about and what we can’t. We learn what is obvious, like how the chocolate on my sweet Junie’s face gave her away. And we learn what is not so obvious. Over the years, we learn clever ways to frame our promises. We cross our fingers behind our back, or we create a false holiday called opposite day. To counteract these loopholes, we invent things like the infamous pinky swear. After all our tricks, we have to figure out ways to get people to trust us. So, we say things like “cross my heart and hope to die… stick a needle in my eye.”

These childish games just continue to grow. In fact, there are actual professions that spend their days writing loopholes in contracts and looking to exploit loopholes in other contracts, or at least they are trained to spot loopholes. Our whole lives, in a sense, are spent learning how to lie. In some instances, it’s a survival tactic or an ego booster. In fact, look at verse 36:

Matthew 5:36 (CSB)

36 Do not swear by your head, because you cannot make a single hair white or black.

Now, when I read this, I thought, what a silly statement. Of course, I can go and make my hair white or black. I can go out and buy a box of Just for Men and comb it right through my beard, and within minutes, I’ll go from grey to black. But this is not at all what Jesus is talking about. Understand, Jesus is not condemning you for dying your hair; please don’t hear what I am not saying. It is not a sin to dye your hair. But what Jesus is getting at is the truth that it doesn't matter what we do to ourselves; ultimately God is sovereign over our bodies. Just a few weeks later, what’s going to happen to my beard? Well, the grey is going to grow back. We can try to lie to others or even to ourselves, but there is nothing that we can do that will change our bodies.

The point Jesus is making here is sometimes in how we speak and how we live, we reflect a sense of control over ourselves that we don’t actually have. And in this one verse, Jesus addresses a deep issue in our culture. I don’t have to tell you that we live in a time and space, in a culture and a society that has adopted the mantra, “My body, my choice.” And God is saying, you can’t say that. Why? Well, it’s not your body! You didn’t create yourself; you don’t own yourself. In fact, your body has been given to you by God, and it’s your job to be a good steward.

You know what else this means? We can’t create for ourselves whatever we want to be. Friends, we can’t even change the hair on our heads, let alone our God-given gender. Now, there are some who, as a result of living in a broken, sinful, and fallen world, struggle with a variety of psychological issues, and one of those issues is Gender Dysphoria. But the answer to this issue is to run to God and His grace, not to take it upon yourself to change yourself. It’s our job as the church to surround people who struggle with these issues, to love them, and care for them, not by affirming their struggle but by pointing them to the truth of the Gospel of Jesus Christ. What they need to hear is that the “freedom” that is offered by individualism is not freedom at all. In fact, the freedom that we all long for can only be found in a God who made us and loves us, in a God who rescues us and gives us a glorious future.

Friend, your God-given identity has been flawed because of sin, but the good news is that God is committed to making it right. We can live today as a part of a wonderful story. Why? Because Jesus the rescuer has come. He lived a perfect life, fully God and fully man. He died; He rose from the dead. And He has sent His Spirit and made the transformation we need possible. It’s true; we are all broken people, broken physically, broken physiologically, and broken in our hearts. But if we trust in Jesus, God has begun a transformation in us which will continue until completion. On that day that we stand before the Lord, we will stand before Him not just in soul but in body, and all the brokenness in our mind, all the brokenness in our body will be no more, for we will be perfectly integrated, body and soul, for the glory of God.

So, as we live life in a broken world that has been marred by sin, rather than trusting our culture, rather than trusting our emotions, rather than trusting that we are who our broken, marred, and sinful feelings say that we are, we trust in God and who He says that we are in His Word. We pursue a life trusting in God’s control over our bodies and live understanding that everything that we say and do takes place before the watchful eye of a sovereign God, who takes, with the greatest seriousness, every word that comes out of our mouths. Why? Well, because it is from our heart that our mouth speaks, and how we speak, the promises we keep or don’t keep, they all speak to the condition of our hearts.

Consider Matthew 12:33-35:

Matthew 12:33–35 (CSB)

33 “Either make the tree good and its fruit will be good, or make the tree bad and its fruit will be bad; for a tree is known by its fruit. 34 Brood of vipers! How can you speak good things when you are evil? For the mouth speaks from the overflow of the heart. 35 A good person produces good things from his storeroom of good, and an evil person produces evil things from his storeroom of evil.

That which the heart thinks, the mouth speaks. Every careless word, every false promise, every broken vow reveals the state of your heart. So, tell me, how is your heart this morning? Are we truly living a life of honesty? Are we sincerely and straightforwardly dealing with others, or are we seeking to deceive? Brothers and sisters, God's commandment is clear. We are to be honest with our speech and to refrain from frivolously using the Lord’s name.

Friends, if your words and false promises reveal a heart that is far from God, the good news is, if you are a Christian, you can turn to the Lord in repentance and faith. In fact, 1 John 1:9 is helpful, for it says,

1 John 1:9 (CSB)

9 If we confess our sins, he is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness.

And if you are not a Christian, you are invited to trust in the only one who is able to replace your cold, hard, and stony heart with a heart of flesh. Simply trust Him.

Romans 10:9–10 (CSB)

9 If you confess with your mouth, “Jesus is Lord,” and believe in your heart that God raised him from the dead, you will be saved. 10 One believes with the heart, resulting in righteousness, and one confesses with the mouth, resulting in salvation.

Now, this leads us to our text's third and final movement.

3. Christ's Call to Gospel Sincerity(v. 37)

In other words.....with all of this in mind....how is it that we are to speak? Well…I am glad you asked....look at Matthew 5:37.

Matthew 5:37 (CSB)

37 But let your ‘yes’ mean ‘yes,’ and your ‘no’ mean ‘no.’ Anything more than this is from the evil one.

So, does this mean we should never, ever make a vow or take an oath? Well, as we've already discussed, the Bible doesn’t explicitly forbid it. We even saw that God Himself took an oath. So......If you find yourself in a context like a court of law, where you are required to take an oath before testifying, you're doing so to reflect the seriousness of the situation. Rest assured, you're not violating Jesus' words here. The point Jesus is making is that our everyday speech should never require an oath or a vow for someone to know we are speaking truthfully.

As followers of Jesus, we are to speak and live with sincerity. In other words, our lives should be free of pretense, deceit, and hypocrisy. We should live such honest lives that we don’t need to swear or make promises to prove we are telling the truth. Jesus goes beyond the letter of the Law; He's pointing out that we usually resort to oaths because, let's face it, we tend to lie. When we say things like 'I swear to God,' we're essentially setting aside a special area of truth and protecting it from our usual dishonesty. In fact, when we use grand, serious oaths, it's often because others expect us to lie in the first place. So, Jesus is urging us to stop cheapening our words with these fancy promises. Instead, we are to pursue radical honesty in everything we say and do.

Helmut Thielicke…a german theologian put it like this:

Whenever I utter the formula “I swear by God,” I am really saying, “Now I’m going to mark off an area of absolute truth and put walls around it to cut it off from the muddy floods of untruthfulness and irresponsibility that ordinarily overruns my speech.” In fact, I am saying even more than this. I am saying that people are expecting me to lie from the start. And just because they are counting on my lying I have to bring up these big guns of oaths and words of honor.

- Helmut Thielicke, Life Can Begin Again (Minneapolis: Fortress, 1980), p. 55.

This sentiment is exactly what Jesus is calling us away from. As we pursue a life that loves Jesus, lives like Jesus, and leads others to Jesus, we should embrace radical truthfulness. Mission Church, we are called to be people of sincerity, where our lives are guided and defined by truthfulness.

We live in a culture that celebrates authenticity. Our culture applauds authentic individuality, but in reality, we're often celebrating people following whatever evil their hearts desire and calling it 'being authentic' or 'living my truth.' As Christians living in such a society, we're not called to live our own truth but to pursue a life that reflects God’s truth. That's the difference between being authentic and sincere. As we pursue a sincere life that reflects the truth of who God is, we don't pretend to be someone we're not. Instead, we recognize that we are sinners saved by God’s grace.

We live in a culture that celebrates authenticity. Our culture applauds authentic individuality, but in reality, we're often celebrating people following whatever evil their hearts desire and calling it 'being authentic' or 'living my truth.' As Christians living in such a society, we're not called to live our own truth but to pursue a life that reflects God’s truth. That's the difference between being authentic and sincere. As we pursue a sincere life that reflects the truth of who God is, we don't pretend to be someone we're not. Instead, we recognize that we are sinners saved by God’s grace.

I am reminded of Romans 3:4

Romans 3:4 (CSB)

4 ... Let God be true, even though everyone is a liar...

According to the Apostle Paul, everyone lies. We're all dishonest; none of us have been entirely truthful, and we have all broken our word. We all have failed to accurately reflect God's truth, and as a result, we all stand condemned before God. As a result.......Some of us need to respond to God’s Word this morning by examining our hearts. Ask yourself, “Is there sin we need to repent of? Is there someone we need to ask forgiveness from? Do we need to recommit ourselves to the truth? Do we need to reconsider how we speak to others? Are there any promises we have made that we need to fulfill?”

And......As we ask ourselves these questions, we do so from a posture of trust in the gospel of Jesus Christ. You see.....Even though we have failed to keep our promises, God has always kept His! Consider with me how...God promised to send Jesus to live the sincere, truthful life we have failed to live and to die for our lies. And....even though we once followed the father of lies, Jesus came to forgive us, cleanse us, and, through the power of His Spirit, transform us into people of sincerity.

This morning, look to the cross of Jesus and see that God’s promises find their ultimate fulfillment in Christ…and..... rest in God’s grace and be encouraged that, for all who have trusted in Jesus as Savior and surrendered to Him as Lord, He is empowering us with His Spirit to live lives of gospel sincerity.

Let's pray.