by John MacArthur
If you’ve spent any time around a toddler, you know that even the simplest, most basic instruction is followed by an unending string of whys. The attitude behind his questions range from inquisitiveness to rebellion, but the inclination to question authority is hardwired into us all.
It’s not enough to be told not to touch the hot stove—we need to know why we shouldn’t touch it. And often, we need firsthand experience of the consequences before we’re willing to do what we’re told. Complete, first-time obedience does not come naturally.
The same is true with the Lord’s commands to believers. We’re not prone to obey immediately, even when He’s clear about the consequences that await our disobedience.
In 1 Thessalonians 4:3-8, Paul spells out the Lord’s command that we abstain from sexual immorality and live pure lives. And he answers the inherent “why” question, telling us what’s in store if we fall short of God’s holy standard.
For this is the will of God, your sanctification; that is, that you abstain from sexual immorality; that each of you know how to possess his own vessel in sanctification and honor, not in lustful passion, like the Gentiles who do not know God; and that no man transgress and defraud his brother in the matter because the Lord is the avenger in all these things, just as we also told you before and solemnly warned you. For God has not called us for the purpose of impurity, but in sanctification. So, he who rejects this is not rejecting man but the God who gives His Holy Spirit to you.
Paul wants us to have a clear understanding of the stakes involved in sexual immorality. It’s not merely a question of individual impurity—there are repercussions for others as well.
We think of defrauding other people in terms of taking advantage of them financially. But the same kind of greedy, selfish thievery happens all the time in relationships. Paul’s instruction is clear—don’t use others for your own gratification.
That’s especially a problem for young people. Young men and women need to be on the lookout for the kinds of predatory people who would take sexual advantage of them. And they need to diligently examine their own hearts to be sure they’re not taking advantage of someone else.
It’s particularly unthinkable that behavior like that would exist within the church, but sadly, it does. Men and women rob each other of their purity and virtue, and they steal from the other person’s future husband or wife.
God’s Word is clear about leading other believers into sin. Matthew 18:6 says, “Whoever causes one of these little ones who believe in Me to stumble, it would be better for him to have a heavy millstone hung around his neck, and to be drowned in the depth of the sea.” We need to cultivate that mindset in ourselves—that the nightmarish horrors of drowning are preferable to causing another believer to sin.
Paul wants us to consider the consequences of sexual sin and to remember the Lord is the one who distributes those consequences. He doesn’t spell out the exact method of God’s vengeance, but the results of sexual sin are destructive and far reaching. It can devastate a marriage, destroy trust and intimacy, or lead to divorce. It can shatter families and all kinds of relationships. It can lead to a variety of temporal troubles, like financial instability or job loss. And it can lead to disease, or even death. There is no end to judgments you heap on yourself when you engage in sexual sin.
In fact, as we saw back in 1 Corinthians 6:9-11, engaging in a continual pattern of sexual sin will bar a person from heaven and consign his eternal soul to torment in hell. Only God’s redemptive grace has delivered us from lives of unbroken impurity. We've been washed and sanctified, and sexual sin is unnecessary. It’s intolerable to God and inconsistent with our new nature.
And when it appears, He has every right to act in holy vengeance. Even an occasional sinful act in the life of a believer will bring about the vengeance of God in this life. It invites the Lord’s chastening.
Sexual immorality contradicts the very purpose that God called us to—we weren’t set aside for impurity, but for purity. We need to be growing closer to the Lord in sanctification, and dalliances with immorality only impede and stifle that growth.
What’s more, that sanctifying work is accomplished by the Holy Spirit, and Paul wants us to remember His constant presence when it comes to abstaining from immorality. Purity isn’t a man-made standard—it was established by God according to His design, and is reinforced by His Spirit at work in us.
The immediate, intimate presence of the Lord ought to be a constant reminder and a powerful deterrent against sexual sin—really, against all sin.
In 1 Corinthians 3:16, Paul confronts believers with this important reminder: “Do you not know that you are a temple of God and that the Spirit of God dwells in you?” Sexual sin doesn’t just defile us—it defames the Spirit that lives and works within us.
That’s why we must abstain from sexual immorality.