Scripture: 1 Thessalonians 4:3–8
3 For this is the will of God, your sanctification: that you abstain from sexual immorality; 4 that each one of you know how to control his own body in holiness and honor, 5 not in the passion of lust like the Gentiles who do not know God; 6 that no one transgress and wrong his brother in this matter, because the Lord is an avenger in all these things, as we told you beforehand and solemnly warned you. 7 For God has not called us for impurity, but in holiness. 8 Therefore whoever disregards this, disregards not man but God, who gives his Holy Spirit to you.
Here is one of the clearest teachings in the Bible on sexual morality, or what used to be called the virtue of chastity. Society is constantly saying that restraining our sexual impulses is at least out of date, if not outright dangerous. But C.S. Lewis argued over 70 years ago:
When an adolescent or an adult is engaged in resisting a conscious desire, he is not dealing with a repression nor is he in the least danger of creating a repression. On the contrary, those who are seriously attempting chastity are more conscious, and soon know a great deal more about their own sexuality than anyone else. They come to know their desires as Wellington knew Napoleon, or as Sherlock Holmes knew Moriarty; as a rat-catcher knows rats or a plumber knows about leaky pipes. Virtue—even attempted virtue—brings light; indulgence brings fog.
Virtue—even attempted virtue—brings light. My aim today is to help us see from these verses that that is true. The virtue of chastity is enlightening. It brings clarity to our souls. It shows us how to live our lives in ways that please God more and more. Chastity is creative. So we should desire chastity, learn chastity, and practice chastity in our daily lives.
First, let’s see the desire for chastity. Notice that verse 3 ties together the command to be chaste to the will of God and to our sanctification. We are told that God’s will—his desire for us—is that we be chaste. And God desires this for us because he wants us to be sanctified. He wants us to be holy. So why should we desire to be chaste? Because God desires it for us and because it is an important aspect of our sanctification.
The Rule of Chastity
Now before we go much further, we do need to remind ourselves what it means to be chaste. We are to “abstain from sexual immorality.” The Bible tells us that sex has an appropriate place and an appropriate purpose. The only appropriate place for sexual behavior is within the covenant of marriage, and the Bible is clear that marriage is the union of one man and one woman for life. And the only appropriate purpose for sexual behavior in marriage is the furthering of what the Bible calls the “one flesh” relationship between a husband and a wife.
The Christian view of sex is often viewed as regressive and out of date in our world today. But it also suffers from a considerable amount of misunderstanding. And this is true, not only outside the church, but inside the church as well. I grew up hearing phrases like, “Stay pure until you are married.” The equating of virginity with holiness is a horrific misunderstanding of chastity. If we are going to see why we must “abstain from sexual immorality,” then we need to see God’s good purposes for sexual morality, not just his good reasons against immorality.
The Will of God
So again, notice the connection to the will of God. If it is God’s will that we “abstain from sexual immorality” it is because it is God’s will that we practice sexual morality.
God is not against sex. He doesn’t want us to avoid talking about it. It is imperative that we talk about it, though of course we should do so appropriately, as Ephesians 5:3 tells us. Parents, you need to be talking about it with your kids. We need to be discussing it together as Christians, like we are doing today. Christian men should get together and discuss the practice of sexual morality, as should Christian women. We should be seeking God’s will together in this matter.
If we believe in the goodness of God and his infinite love for us, then the will of God must never be spoken of as though we have to concede to it, that doing what God says is a loss. What God wants for us is the very best thing we could ever have. God is certainly not prudish when it comes to sexuality. Neither should we be.
Sanctified in Sexuality
Chastity is the will of God for us because, verse 3 tells us, it is an important aspect of our sanctification. Catechism question 31 tells us what sanctification is:
Sanctification is the work of God’s free grace by which our whole person is made new in the image of God, and we are made more and more able to become dead to sin and alive to righteousness.
Sanctification is a benefit we receive from being united to Christ. It is a gift of grace, a gift by which “our whole person is made new in the image of God.” Our whole person. That includes your mind, and that includes your body. And this gift of grace makes us “more and more able to become dead to sin”—to abstain from sexual immorality in this context—and it makes us “more and more able to become . . . alive to righteousness”—to be chaste.
So God wants us to be chaste, and graciously gives us the power to be chaste. So you must be chaste.
But chastity is an aspect of our sanctification, and it is not easy. God knows this. Sexual sin is sin, but it is not the unpardonable sin. Unfortunately, the church often acts like it is. We are way too fast to condemn the sexual sinner while giving other sinners a pass.
Look, the goal here is not to be a “chaste Pharisee,” and virginity does not make you holy; we are all “imperfect disciples” who are learning, by God’s grace, to be chaste.
No one is born chaste. As a result of the fall, we are all broken in our sexuality. All of us. And marriage doesn’t solve the problem, so we are all in the same boat here. As an aspect of our discipleship, we all need to not only desire chastity. We all need to learn chastity.
All Have Sinned Sexually
Verse 3 tells us that it is God’s will that we abstain from sexual immorality. But verse 4 says that God’s will is also “that each one of you know how to control his own body in holiness and honor.” These are not two different things that God wills for us; rather verse four is the antidote to sexual immorality.  How can I abstain from sexual immorality? By learning how to control my body in holiness and honor.
Again it needs to be said that this is the calling for each one of us. Whether you are young or old, married or single, whether you appear to be free from sexual sin or are a known sex offender, let each of us learn how to control our own bodies in holiness and honor.
I am a sexual sinner. And so are you. The church is for sexual sinners.
On the other hand, we cannot learn chastity only by talking about our failures in it. No one ever masters anything only by knowing what not to do. How can we learn chastity?
A Creative Mess
Verse 5 gives us some direction here. Notice that the control of the body in verse 4 is contrasted with “the passion of lust” that describes “the Gentiles who do not know God.” In other words, when it comes to sexual morality, Christians are supposed to be distinct from the way non-Christians act. We are supposed to be separate; that’s the whole idea of sanctification.
Of course not all non-Christians behave the same way. But the way Paul describes them here is always an accurate description of the non-Christian perspective on sexuality. Without a knowledge of God, all you have left is to act in “the passion of lust.” Paul is referring to what non-Christians do with their sexual desires and impulses. And he says that because they do not know God, they simply let them go wherever they want. Indeed, it seems that the unregenerate mind comes up with more and more ways to push against boundaries and cultural norms.
But Paul says that the promiscuity that comes from any cultural sexual revolution is not creative, not in the sense of it being admirable and beautiful. There is nothing admirable about gorging yourself to death. There is nothing beautiful about creating a mess. Creating a mess? Now that’s an irony for sure.
The Beauty of Restraint
There’s nothing interesting about yielding to every impulse that comes from your desires. There is nothing worth seeing there. You never get much of a crowd to watch a bunch of novices compete at some sport. It is not gluttons who are beautiful at gymnastics but disciplined athletes. And we marvel at their self-control. We want to be like them. But when it comes to the control of our bodies in our sexuality, we’ve fallen for a lie.
C.S. Lewis observed that this “lie consists in the suggestion that any sexual act to which you are tempted at the moment is also healthy and normal.” But if you just stop and think about it, even without Christian morality we know this is sheer nonsense. He writes:
Surrender to all our desires obviously leads to impotence, disease, jealousies, lies, concealment, and everything that is the reverse of health, good humour, and frankness. For any happiness, even in this world, quite a lot of restraint is going to be necessary . . . . Every sane and civilised man must have some set of principles by which he chooses to reject some of his desires and to permit others.
Lewis said that the real conflict on this issue is not between Christianity and human desires but between Christian principles and other principles in the control of those desires. One way or another, natural desire will have to be controlled, said Lewis, “unless you are going to ruin your whole life.” He admits that the Christian principles of chastity are stricter than what society ever gives us, but then again it is Christianity which provides “help towards obeying them” says Lewis, “which you will not get towards obeying others.”
Knowing God and Learning Together
This is exactly what Paul says. If you are a Christian, then you are not a slave to your passions. Why? Because you know God. Notice it is only because you are in this relationship with God that you have the power to learn chastity. Chastity is not the means by which you enter into a relationship with God. Rather, Christ died for you, brothers and sisters, Christ entered into a covenant relationship with you when you were not chaste.
And it is this real, vital relationship that gives you the power to learn chastity, to control your body in holiness and honor. As Paul says elsewhere, “walk by the Spirit, and you will not gratify the desires of the flesh” (Gal 5:16).
So how do you do it? How do you “abstain from sexual immorality” in mind and body? How do you control your body in holiness and honor? How do you “walk by the Spirit” in this matter? We need to learn how to do it together, because this is a matter of Christian wisdom. We need to be creative. Creative chastity. In other words, this is not a private matter. We’ve got to learn from each other.
The church is the place to learn chastity. This is the place for us to practice chastity. Verses 6-8 give us direction how to do it.
First, we need grace, plenty of grace, to practice it. Verse 6 says that we need to practice chastity so “that no one transgress and wrong his brother in this matter.”
It seems that Paul wrote these verses in his letter because in the church at Thessalonica there were some who had had an affair with other members in the church. So after all he has said about the amazing evidence of God’s grace at work in this church, here we find that there was significant sexual sin also evident there.
If we are going to practice chastity we’re going to need to extend a lot of grace to one another. To those who know you are broken sexually, who feel defeated by sexual sin, who are afraid they will never overcome it, and who wonder if God could ever accept them because of it, I say to you that God’s grace is greater than your sexual sin! The church should be a place for sexual sinners to find hope in the grace of God.
I know the words at the end of verse 6 are terrifying, as they should be: “the Lord is an avenger in all these things.” But the point here is that chastity is a spiritual concern. Whatever our culture says about it doesn’t matter. Whatever someone else in the church says about it doesn’t matter. We know what God’s will for us is in this matter. God cares about our chastity because he cares about our holiness. As verse 7 says, this is what he has saved us for!
So we should not think of God’s grace as his love for us in spite of our sin, as if God doesn’t care if we continue to sin or not. The grace of God is the promise that, safe in his unfailing love in spite of your sin, he will begin, day by day, to transform you into his image. He is sanctifying us.
Yes, he will do it. So don’t give up. However far into sexual sin you may be, don’t give up! But one way to give up is to stay in hiding, to think that you can conquer this sin on your own, to think of your sexual sin as a personal issue. You need to seek help.
The Help of the Holy Spirit
As verse 8 reminds us, God has given to us, literally, “his Spirit who is holy.” The emphasis is placed on the holiness of God’s Spirit who indwells us. If you come to Christ, you will receive the help you need to be holy, to practice chastity.
So you must not say, “God cannot love me, because I am such a sexual sinner.” To say this is to reject not man, but God. It is to reject the gospel of God’s amazing grace for sinners.
But you also must not say, “God loves me in spite of my sin, so I do not need to be chaste.” To say this is also to reject not man, but God. It is to reject the same gospel of God’s amazing grace that sets sinners free from the power of sin.
Jesus showed amazing, forgiving grace to the woman caught in adultery when he said, “Neither do I condemn you.” But he also showed amazing, sanctifying grace to her when he said, “Go, and from now on sin no more” (Jn 8:11).
So, brothers and sisters, let us desire chastity, because it is God’s will for us. Let us learn chastity, because we are all sexual sinners. And let us practice chastity because God has given to us all the grace—all the help—we need to live holy and chaste lives.
 Jen Pollock Michel, “Don’t Overstate the Rewards of Sexual Faithfulness. Don’t Understate Them Either,” Christianity Today, November 15, 2020, available at www.christianitytoday.com/ct/ 2020/november-web-only/talking-back-purity-culture-rachel-joy-welcher.html.
 The translation in the ESV, “control his own body,” are the best interpretation of the more ambiguous literal reading: “to get his own vessel.” It is possible that the phrase refers to how one ought to “get a wife,” since the word “vessel” refers to a wife in 1 Pet 3:7, but the subject here is not marriage but chastity. The word “vessel” is also used to refer to a human person in general in 2 Tim 2:21, and in a context far more similar to this one (see 2 Tim 2:22). Since the verb can mean not only “to get” or “to acquire” but also “to control,” it fits the context more naturally to read it that way.