SermonOnTheMountEditor’s note: The purpose of this series is to walk our readers through the Sermon on the Mount in Matthew 5-7 in order to help them understand what it teaches and how to apply it to our lives. This is our first such series here at Servants of Grace through an extended biblical passage and is part of our larger commitment to help Christians learn to read, interpret, reflect, and apply the Bible to their own lives.

In this section of the Sermon on the Mount, Jesus’ teaching moves from one challenging topic to the next. After addressing anger, He moves on to lust, to marriage and divorce, and now to speech, especially careless and deceptive speech in Matthew 5:33-37. As always, His interests go through our deeds to our hearts.

The Need for Jesus’ Teaching

Truthfulness is Jesus’ central concern in this passage, and He knows that we struggle with veracity. “Talk is cheap,” we say, for we are careless with our words—even with our promises. Politicians are renowned for breaking promises. A presidential candidate once won election, in part, on his bold promise, “Read my lips: no new taxes.” Two years later, he signed a large tax increase.

Ordinary folks do the same thing. Businessmen call home and say, “It’s been a busy day, but I will still be home by 6:00, 6:15 at the latest, 6:30 at the very latest. I’ll call if I’m delayed.” Almost half of us even violate the sacred promise: “I promise to take you as my lawful, wedded wife till death do us part.” Clearly, we need Jesus’ word about our words, from Matthew 5:33–37:

Again, you have heard that it was said to the people long ago, “Do not break your oath, but keep the oaths you have made to the Lord.” But I tell you, Do not swear at all: either by heaven, for it is God’s throne; or by the earth, for it is his footstool; or by Jerusalem, for it is the city of the Great King. And do not swear by your head, for you cannot make even one hair white or black. Simply let your “Yes” be “Yes,” and your “No,” “No”; anything beyond this comes from the evil one.

Jesus’ Teaching on Oaths in Context

In Matthew 5, Jesus tells His disciples, “I tell you that unless your righteousness surpasses that of the Pharisees and the teachers of the law, you will certainly not enter the kingdom of heaven” (Matthew 5:20). The scribes and Pharisees were famed for their impeccable observance of the law’s external regulations, as they understood them, so the disciples must have wondered how they could surpass them. But Jesus does not ask His disciples to surpass the Pharisees by obeying more regulations. A disciple’s surpassing righteousness is not essentially a matter of legal observance. Remember, Jesus points beyond the act of murder to the problem of anger. He points beyond adultery to lust. Here He points beyond oaths to truth-telling.

Jesus does not urge us to redouble our efforts to observe the law. Nonetheless, we must let His moral teaching have its weight. If God’s commands are difficult, we need to face that squarely, confess it to ourselves and to God, and ask for mercy.

Many people prefer less candor. They deny that God’s will is so clear. Or they redefine the law so it is easier to obey. In Jesus’ day, the Pharisees tended to do that. When they faced a difficult law, they whittled it down to something manageable. We are prone to do the same sort of thing, redefining Jesus’ commands to make them more manageable.

When the rabbis heard “Love your neighbor as yourself,” they defined “neighbor” narrowly, so that only a small percentage of people counted as neighbors. If most people did not count as neighbors, then perhaps they could love the few that were left. When the rabbis read “You shall not commit adultery,” they refrained from literal adultery, but reserved the right to divorce their wife and take another woman at any time. Thus, they removed much of the temptation to commit adultery by making it legal to divorce one woman and take another whenever they pleased. They did much the same thing with oaths and truthfulness. Jesus corrects these abuses by expounding the true meaning of the law. Therefore he argues, “You have heard that it was said … but I tell you …”

The Nature and Use of Oaths

At the most basic level, Jesus tells His disciples that they must tell the truth, but Jesus reaches that principle by discussing the matter of oaths. Oaths are a convention designed to restrain lies and false promises. We rarely use oaths or vows today. We reserve them for formal situations. We take oaths when we join the church or become an officer, when we get married, and when we are called to testify in court. While we rarely take oaths today, we use similar conventions with the same goal. We make promises to friends and family, and we sign contracts in business dealings. Oaths, promises, and contracts all have the same goal—to induce people to tell the truth and be true to their word, especially when there are temptations to lie or to break a commitment.

In biblical times, oaths and vows were more prominent. Long ago, Israel learned to guarantee their veracity by swearing, in God’s presence and in His name, to tell the truth (1 Sam. 12:3; Prov. 29:24). They invoked God as a witness, and they invoked Him as judge if they lied. If someone swore that something was true, it had to be true. If someone vowed to perform a deed, it had to be done.

Jesus summarizes the Old Testament lesson when he says, “You have heard that it was said …, ‘Do not break your oath, but keep the oaths you have made to the Lord’ ” (Matt. 5:33). Jesus understood that several Old Testament laws blessed and regulated the use of oaths and vows:

  • “When a man makes a vow to the Lord … he must not break his word” (Num. 30:2).
  • “If you make a vow to the Lord your God, do not be slow to pay it” (Deut. 23:21).
  • “You shall not swear by my name falsely, and so profane the name of your God” (Lev. 19:12 ESV).

It is still God’s will that we do what we say, especially in solemn settings, when others depend on our words. Even if circumstances change, even if we get a better offer, even if faithfulness becomes difficult, even if the temptation to break a vow seems unbearable, even if keeping the vow brings real loss, even if no one but God will know if we break our vow, we should still do what we say. We should disregard a vow only if keeping it requires us to sin.

The Abuse of Oaths

The teaching on vows seems helpful; why then does Jesus want to amend it? First, in Jesus’ day, rabbis concocted a convoluted system that defeated the very purpose of oaths. They said that oaths might or might not be binding, depending on what one swore by. They said that if one swore by Jerusalem, it is not binding, but if one swore toward Jerusalem, it is. If one swore by the temple, it is not binding, but if one swore by the temple’s gold, it is. If one swore by the altar of sacrifice, it is not binding, but if one swore by the gift on the altar, it is.

These strange rulings perverted the purpose of oaths. Instead of calling on God to assure one’s honesty, one phrased oaths so as to avoid God’s punishment when one spoke dishonestly. Perhaps no one planned to corrupt the law, but the rabbis spoiled the goal of verifying truthfulness and substituted the goal of getting away with deceitfulness.

Since the system was corrupt, since oaths no longer guaranteed anything, Jesus said, “Do not swear at all” (Matt. 5:34a). He removed the artificial distinction between vows that invoke God’s name (and so are binding) and those that do not (and so are not binding). Whatever we swear by, Jesus said, it refers to God, for He created heaven and earth. If someone swears by heaven, he invokes God, for heaven is His throne (Matthew 5:34b). If someone swears by the earth, he invokes God, for it is His footstool (Matthew 5:35a). If someone swears by Jerusalem, he invokes God, for it is the city of the King (Matthew 5:35b). If someone swears by the hair of his/her head, he/she invokes God, for He rules our heads (Matthew 5:36).

Jesus says, “Do not swear by your head, for you cannot make even one hair white or black” (Matthew 5:36). Of course, we can change our hair color by applying certain chemicals at the salon. But we cannot change the natural color of even one hair. Whatever we swear by is related to God in some way. All oaths call God as our witness, for He created and sustains all things, even our hair and its color.

What God’s Oaths Reveal

Jesus’ disciples should simply tell the truth. The Essenes said, “He who cannot be believed without [swearing by] God, is already condemned.” Jesus said that we should be so true to our words that the need for oaths disappears, that a simple “Yes” or “No” is enough. The word of a disciple should be so reliable that no one asks for more.

This leads to an important question. If Jesus wants disciples to take no oaths, why does God take oaths, apparently violating His own ideal? For God does takes oaths:

  • He said to Abraham, “By myself I have sworn … I will surely bless you” (Gen. 22:16–17 ESV).
  • God confirmed his promises to Israel “with an oath” (Heb. 6:17).
  • God swore to mankind that he would never send another flood (Gen. 9:8–11).
  • He swore to send a Redeemer (Luke 1:68, 73) and to raise him from the dead (Ps. 16:10; Acts 2:27–31).
  • God took oaths to guarantee his covenants (Pss. 132:11; Psalm 95:11; Psalm 119:106).

Why does God do something that he tells us not to do? John Stott replies, “Not to increase his credibility but to elicit and confirm our faith.” God does not take oaths because His credibility is in doubt, but because we, having told and heard so many lies, have learned to be doubters. We are accustomed to breaking our word and having others break their word to us. Therefore, God knows that we need assurance of His reliability. He knows that our standards are so low that we expect falsehood from everyone, even Him. So for our sake He takes an oath to guarantee His word.

What Our Oaths Reveal

If God’s oaths reveal that we are accustomed to hearing lies, what do our oaths reveal? Let us answer by considering something similar—the promise. Consider why we make promises. Suppose it is Thursday evening. A father tells his children, “If you help me clean up the yard today, I will take you out for ice cream on Saturday.” A wary child may reply, “Do you promise?”

The request for a promise is a testimony against us. It shows that a child has learned she cannot entirely trust her father’s word. In the past, she cleaned up the yard, but never received the ice cream. When the child pointed this out, her father said, “I forgot,” or “Something came up,” or “You should have reminded me.” So the child learned to seek a guarantee. When she asks, “Do you promise?” she means, “Do you mean it? Can I count on you?”

The very request for a promise testifies that we are not reliable. When a child asks, “Do you promise?” he testifies that our “Yes” has not always been “Yes.” Ideally, a parent’s word should be so reliable that it never occurs to a child to request a guarantee. Our word should be so reliable that our “Yes” does mean “Yes” (not “Probably”), and our “No” does mean “No.” Then the need for oaths and promises should wither away.

The very existence of customs such as oaths and promises reveals that human life is tainted by deception. Jesus says that the family of God should be an exception to this. In the Kingdom, we should be so truthful that we need neither promises nor vows.

The Use of Oaths Today

This leads to a practical question: may disciples take oaths today? I believe we may, although a few Christians disagree. They say we must take Jesus’ words literally and take no vows. To take any military or civic position, we must swear an oath of loyalty to the nation and its laws. Therefore, this position entails a willingness to forgo all public service.

Most Christians take a different approach. Following Luther and Calvin, among others, we distinguish between public and private speech. In private, among friends and brothers, we should simply tell the truth, so that the need for oaths disappears. Yet, since God Himself sometimes swears oaths for the sake of His doubting listeners, we can take oaths for the sake of our doubting listeners.

Oaths are never ideal, but the law permits and regulates them (as we saw earlier) because oaths can make us think twice before we speak, thereby encouraging us to be truthful. Much of the law—both God’s law and civil law—has the same goal of regulating and mitigating the effects of sin. Laws about such things as divorce, oaths, and property, not to mention the entire penal code, do not describe God’s perfect will, but rein in the effects of sin.

Here then are standards for disciples. First, let us be so truthful that someone who knows us well would never solicit a vow from us. On the other hand, we may take a vow to grant assurances to someone who does not know us. God took vows to aid those who did not know how reliable He is. For the same reason, Jesus spoke under oath at his trial (Matt. 26:63–64). Paul also took vows, calling God as his witness (Rom. 1:9; 2 Cor. 1:23; 1 Thess. 2:10). Therefore, for the sake of people who do not know that we are reliable, we may take vows.

Second, for the same reason, we may take oaths and vows in the courtroom, or before entering military or political service. The alternative is that Christians would forfeit most of their influence on public life. They would also have to rethink many commercial transactions, since contracts resemble oaths.

There is a third, broader lesson. By permitting and regulating oaths, God permits us to get involved in the dirt and the mess of public life. He does not say, “Withdraw, lest your hands be touched by evil.” We have already been touched by evil. Now we are the light of the world. In a “crooked and depraved generation” we “shine like stars in the universe” (Phil. 2:15). To take an oath is to get involved in the world of liars. We bring the transforming power of God to that world, but we may get a little dirty there. In the Old Testament, Joseph, Daniel, Ezra, and Nehemiah got involved and got dirty, but also accomplished great things.

Christians do not spend all their time in the ideal world. The disciple’s goal is that his/her words be so reliable that people do not even think to ask, “Do you promise?” Then we will never need oaths. But when people do not know us, when the habit of lying is old and the pressure to lie is strong, we may take an oath to guarantee our word.

Why Telling the Truth Is a Challenge

So Jesus wants us to tell the truth; we probably want to, too. Why then do we fail? Consider two reasons: carelessness with our words and fear of telling hard truths. Cowardice in speech refuses to bring bad news to someone face to face.

Cowardice is telling people what you think they want to hear, whether it is true or not. Cowardice is bringing good news in person, but sending bad news in memos. Cowardice is criticizing someone at lunch and hoping it gets back to them. Courage is telling the truth as plainly and purely as possible, whether it is pleasant or not.

Most of us want people to like us, so we want to bring good news. We think we are being nice when we do. But in the end it is cruel, not kind, to refuse to bear news that is bad, but necessary.

Imagine that a woman awakens one day with a severe headache. It persists, so she visits her physician. Her doctor performs tests that reveal cancer. But the physician is a sensitive man. He hates to see people shattered by such diagnoses. So he calls the woman in and says, “Ma’am, I can see why you might be having these headaches, but I want to assure you that within a few months you won’t be feeling a thing.” When we fail to tell a hard truth, we are cruel, not kind.

People who have worked both for a truth-teller and for a people-pleaser ordinarily prefer the leader who brings bad news promptly (yet tenderly) and keeps small promises rather than merely making big promises. It is good to know where we stand and what to expect. It is the way of Christ, who never withheld the bad news about sin and who kept every promise he made, no matter what the cost.

Our culture encourages careless speech. We take words lightly today. Older businessmen lament the end of the era when a man’s word was his bond. We live in a world of print and computer screens, a culture of text. We say, “Talk is cheap,” and “I want to see it in black and white.” If it’s in print, we think it counts more. We need to revalue the word spoken, so that it has the same value as the word written.

Some of us talk so much that we hardly pay attention to ourselves. The church must regain God’s view of the sanctity of words. As James says, we should be “slow to speak,” careful to weigh our own words. Most of us rarely tell a direct, deliberate lie. Months may go by without anything worse than exaggeration or the omission of a key detail. But we do squeeze the truth and evade it and exaggerate it to our benefit.

We also redefine the truth to our advantage. In The Diary of Anne Frank, there is a scene where eight Jews are hiding in a small, hidden room in a large house. There is not enough space, and the fear of getting caught leads to enormous stress. A married couple adds to everyone’s anxiety by bickering constantly. At length, an exasperated member of the group asks them to stop quarreling. They immediately reply, “This isn’t a quarrel, it’s a discussion.” Just so, we try to change reality by redefining it.

To the Heart of the Matter

The standards for oaths and promises are now clear enough. We know it is our duty to prove so faithful to our word that the use of oaths and promises withers away. But a problem remains. Although we know that we should keep our word, we bend or break the truth anyway. Why? Why do we make promises that we scarcely intend to keep? Is it a shallow desire to please others? Is it a device that we use to escape difficult conversations, so that when someone presses us, we finally say we will do something just to get rid of him?

Sometimes we falter through folly more than sin. We fail to keep our word because we fail to anticipate readily foreseeable obstacles to keeping it. We could have kept our word if no problems had arisen. But obstacles do arise. Thus, our failure is due to folly more than malice.

But other failures are not so innocent. Consider when we are most prone to break a promise. We violate words spoken to the powerless—such as a child—much more than we break promises spoken to the powerful—such as a boss. We break less visible commitments, such as nursery duty, and keep more highly visible ones, such as leading a meeting.

Then there is the problem of exaggeration. We heighten our sorrows to gain sympathy. We exaggerate the hours spent at work. We puff up statistics to make an impression. We may not tell many big fat lies. We rarely take a blunderbuss and blast a hole through the truth. But we do slay the truth with a thousand paper cuts. However we try, flawed humans cannot always tell the truth just as it needs to be told. It is like trying to drink coffee with a fork. It can’t be done.

The Final Goal: Perfection

Jesus wanted us to draw the conclusion that we are unable to keep His demands. For the longer His sermon goes on, the more demanding it gets. Watch how the challenge of Jesus’ teaching grows progressively more difficult:

  • Matthew 5:31–32. Jesus’ first word is about marriage; He tells us how to treat one who is nearest and dearest to us.
  • Matthew 5:33–37. The second command deals with the truth, which we must tell our neighbors.
  • Matthew 5:38–42. Third, He declares that we owe mercy, not vengeance, to someone who harms us. This may be feasible in some cases, since some harm is accidental.
  • Matthew 5:43–47. Finally, Jesus tells us to love our enemies, to love those who harm us by design.

Jesus’ last word is harder still: “Be perfect, therefore, as your heavenly Father is perfect” (Matthew 5:48). The standards of Jesus’ sermon are too high for us. We have neither the purity of heart nor the character that it demands. In this way, Jesus’ teaching drives us to the gospel. We must try, and we do try, to lay aside anger and lust and falsehood. But as we try, we see that sin is like kudzu. The root is so deep. No one can kill it. We are incapable of following our Lord’s standards. Therefore, we need our Lord’s grace.

We need the gospel. It teaches us to ask the One who gives the standard to forgive us for breaking it. We ask the One who kept the standard in perfect righteousness to give us His righteousness and clothe us with it. And the Lord does it. He accepts us as His children and grants us the family resemblance that He requires. For the hardest command is also stated in a way that gives hope. Translated literally, Matthew 5:48 states, “You shall be perfect as your Father in heaven is perfect.” We rightly read the words “You shall be perfect” as a command, yet, reading it again, we notice that it hides a promise: you shall be perfect.

In Christ, we are a new creation, yet we await a wholly new creation. There is a future for the disciple, and that future draws us forward. We lean toward that future, and it both beckons us and spurs us onward. In fact, the Sermon on the Mount has many promises about the future of a disciple: We shall inherit the earth (Matthew 5:5). We shall receive mercy (Matthew 5:7). We shall see God (Matthew 5:8). We shall be called sons of God (Matthew 5:9). We shall be perfect (Matthew 5:48). God is in heaven, so His moral excellence vastly exceeds our pitiful attempts at holiness. Yet He is our Father. He has come near to love us and to bring us to maturity.

So let us hear Jesus’ call to truthfulness. Let us measure our words and speak carefully, so that “Yes” means “Yes.” Let us describe events without the distortions, theatrics, embellishments, and exaggerations that mislead our neighbors. Let us not claim to know what we do not know. Let us measure each promise so that we mean what we say. Our families, our churches, our society, will be stronger for it.

Yet let us also admit that, strive as we will, we will never master the tongue. The tongue is too loose, the heart is too wild. So after we hear the law of Christ, let us plead for the grace of Christ. May He forgive our sins.

Each Christian is also part of a larger family. That family is founded on perfect truth-telling. God the Father tells us the painful truth about ourselves: we are sinners, we fall short of God’s holy standards, and we are unable to reform ourselves so we can meet those standards.

The Father also made a sweet promise to send a Redeemer, to deliver us from sin. He kept that promise, though it was painful to Him. If God is your Father, you now belong to a family that tells the truth in love. He is building a new society, where we tell hard truths in love, so we can fix problems. We tell happy truths without adding flattery to gain a favor. As a result, we trust each other’s words. Truth-telling works, of course. But we have another reason to tell the truth: we are children of the Father, who tells us the truth about Himself, about us, and about our relationship with Him.