Sexual sin is the Apostle's subject in our text, I Thessalonians 4:3-8. After a serious introduction (verses 1 and 2), he moves right into the urgent matter:

"It is God’s will that you should be sanctified: that you should avoid sexual immorality," verse 3.

The Thessalonians needed this warning - just as we need it today. Sexual looseness in the first century Roman Empire is still proverbial. Fornication was scarcely noticed -- even playing a part in their religion!

Paul had his task cut out for him. And, today, nothing short of God's Spirit can make men sense how evil immorality is. Here is Scripture insisting impurity must be avoided with great care, but on every hand today it is laughed at as true comedy. It is applauded as manly, or the really womanly thing.

In the bed of immorality, many seek a romantic dream only to awaken with a horrible nightmare. Even if one dreams on, what God says is inevitably true. Illicit sex is sin. One of the deadly sins.

Little wonder, then, when Paul speaks of "sanctification", he simply has to bring up the matter of immorality. Sanctification is the process whereby God carries us on in holiness, to true sainthood. This will, among other things, surely involve your "sex life."

Spiritual growth means first of all, as one translation puts it, "a clean cut with sexual impurity."  Sex sins are serious sins. Our text sets forth three deadly serious facts about immorality:

I. AGAINST GOD

Put God in the picture and you will at once see that impurity is sin against Him.  What does God say? That is the matter. Nor, is it whether another is offended or consenting. Is God offended? What does God say about it in His Word?

Verse 3 says clearly God wills for us to keep from sexual sins. Then verse 7 says we are called by God for a specific purpose. That is, He chose you. Why? Not to be impure, and to debase the body and break His commands. But we are to live holy lives - free from those stains.

"Therefore, anyone who rejects this instruction does not reject a human being but God, the very God who gives you his Holy Spirit," 8. See the grave danger of disregarding this teaching about sexual purity. That would mean we would be rejecting, grieving that very Spirit of God who alone saves us. "Do you not know that your bodies are temples of the Holy Spirit, who is in you, whom you have received from God? You are not your own," I Cor. 6:19.

II. AGAINST OTHERS

Verse 6 makes it clear that sex sins are serious because they wrong others.
"and that in this matter no one should wrong or take advantage of a brother or sister. "

Many are harmed directly in ways that can never be undone. An entire life turned around and headed toward ruin. How awful to call it "love" when it destroys peace and purity and leads one into marriage with a twisted outlook and cheapened life. Then, after marriage, whenever there is cheating of any kind, the  blessing goes and the curse comes. If you have cheated on your partner, take these steps: l) Call it sin and seek the forgiveness of God. 2) Make the necessary restitution, according to Mat. 5:23, 24. Tell your partner exactly what you have done. Remember time never cancels a debt. Make it right.

"I don't involve others in my sex failure," someone objects. Perhaps you don't, but they are still harmed indirectly. Those secret pornographic "trips," the self-centered stimulation of one's own body for sex-pleasure is destructive. It fogs and tenses the personality and ultimately cheats and hurts others around  you.

"The Lord will punish all those who commit such sins, as we told you and warned you before," the Apostle adds. What a solemn, urgent, needed word this is. Hear it!

III. AGAINST ONE'S OWN BODY

No doubt the New International Version is accurate in its rendering of verse 4: "That each of you should learn to control his own body." Plainly, God holds us responsible to learn the way of godliness in sexual areas. Everywhere  Scripture teaches that sexual relationships are legitimate only within the bonds of marriage. There it is blessed of God. Apart from that it is punished by God.

Those who abuse their bodies by indulging in promiscuous sex will receive punishment in their own bodies, minds and emotions. Read it in Romans 1:24-32. Little does it matter if one seems to escape. Delayed judgment is still certain judgment.

Hearing an old man boast that his secret to longevity is wine, women and song is like the foolish mouse in the cat's paw peeping, "Look at me, I'm still alive; it's all a funny game." He who lives in the cat's paw will die in the cat's mouth. And, the man who lives in sexual looseness will be slain in everlasting judgment. God says so.

Instead, a man ought to bring his own body and its desires under control and live "in a way that is holy and honorable," verse four adds. Impurity brings shame and dishonors our own body, according to Rom. 1:24.

Next, our text (verse 5) orders that we are not to live "in passionate lust like the pagans, who do not know God." When passions are aroused the reason becomes passive and is carried down a wrong way. Feelings overpower the mind.

"Flee from sexual immorality. All other sins a person commits are outside the body, but whoever sins sexually, sins against their own body," I Corinthians 6:18.

Looking back at our text, end of verse 5, shows that such behavior is heathen-like. It indicates no knowledge of God. Your attitude toward these physical matters, then is a prime concern of Christianity. God cares about your sex life.  If there is sin there, you are actually saying, "I don't really know God." And, you are grieving the Holy Spirit, 8.

I call on you now to repent of the sins of immorality. Impurity in its many forms is terribly serious. Our Savior shed His blood to pay for this sin. Claim that offering, and determine further to ask for His purity. Nothing short of the mind of Christ, brought into us through the Holy Spirit, can bring full purity and peace. Amen!