Knowing God is the Path to Purity

John Piper, in a sermon on 1 Thessalonians 4, “This is the Will of God For You: That You Abstain From Sexual Immorality”

Start reading with me at [1Thessalonians 4] verse 4: “That each of you know how to possess his own vessel in sanctification and honor, 5 not in lustful passion, like the Gentiles who do not know God.” There it is: “like the gentiles who do not know God.” When you give way to lustful passion, you act like people “who do not know God.” Which means: knowing God is the path to sexual purity. If you are struggling with sexual impurity in mind or body, the immediate and long term strategy is know God, know God!

Be careful here! Don’t nullify 1 Thessalonians 4:5 by saying with a cynical tone: “Good grief, there are world-class theologians who are in bondage to lust and who leave their wives. So what good is all this knowledge about God?” Indeed there are. And I say with tremendous confidence: they don’t know God. To know ten thousand facts about God is not to know God.

Knowing God is the path to sexual purity. And if you are in bondage to pornography and fantasies or fornication or adultery the immediate and long-term strategy of this war is: Know God! Know God! Lustful passion is the mark of the Gentiles who do not know God. (See 1 Peter 1:14; Ephesians 4:22; Romans 1:23-28.)

Why would this be? Why would God ordain that the path to sexual purity is knowing God? The answer is given in 1 Corinthians 6:18-20,

“Flee from sexual immorality. Every other sin a person commits is outside the body, but the sexually immoral person sins against his own body. 19 Or do you not know that your body is a temple of the Holy Spirit within you, whom you have from God? You are not your own, 20 for you were bought with a price. So glorify God in your body.” Or verse 13: “The body is not for immorality, but for the Lord, and the Lord is for the body.”

We have bodies so that God might be gloried in them. That is why God gave you a body – whether it’s tall or short, pretty or plain, brawny or feeble. This is what Paul said in Philippians 1:20, “It is my eager expectation and hope that Christ will . . . be exalted in my body, whether by life or by death.” Our bodies are given to us so that in the way we use them Christ is made to look more valuable to us than anything.

Now we can see why it is that Paul would say that knowing God is so crucial in the war on lust and pornography and fornication and adultery. If, by some means you get rid of lustful thoughts and slavery to pornography and fornication and adultery – without any reference to the knowledge of God, he won’t get any glory for your new behavior. In other words, God is not just interested in what you do with your body, he is interested in – he is passionately concerned with – why you do it. If there is no connection between your knowing God, and your sexual purity, God gets no glory and you are in the grip of another idol.

Knowing God is the path to sexual purity because the purpose of sex and the purpose of the body is to magnify the supreme worth of God and the infinite value of Jesus Christ. And he will not be seen as supremely worthy and infinitely valuable if knowing him is not the key and the path of our liberation. “You will know the truth and the truth will set you free” (John 8:32). And Jesus said, “I am the way the truth and the life” (John 14:6). Knowing God, knowing Christ, is the path to sexual purity.

But we should ask in closing: Knowing what about him? Knowing him in what way? Let me mention three things about God that he may use to set you free and keep you free.

Know the Patience of God

Look at verse 1: “Finally then, brethren, we request and exhort you in the Lord Jesus, that as you received from us instruction as to how you ought to walk and please God (just as you actually do walk), that you excel still more.” Do you see what this says about God? It says, these Christians have room for improvement – “excel still more and more.” And it says that they are pleasing God – “just as your actually do walk.” In Christ, God is not an all or nothing God. He knows our frame. He covers our sin. He is pleased with our successes through faith, and patient with our failures. So know him in his patience, all you struggling saints. Let this knowledge encourage you: You are walking in the way that pleases him – do so still more and more.

Know the Power of God

In the previous chapter, 1 Thessalonians 3:12-13, we read Paul’s prayer for the Thessalonians: “May the Lord make you increase and abound in love for one another and for all, as we do for you, 13 so that he may establish your hearts blameless in holiness before our God and Father, at the coming of our Lord Jesus with all his saints.” Notice: he asked Christ to establish them blameless in holiness at his coming. In other words, holiness is the work of Christ. Yes, we must pray for it, and yes, we must fight for it. But in the end, be encouraged! You are not left to yourself to win this war. Know God’s power on your behalf through Jesus Christ.

Know the Preciousness of God and the Pleasure He Is to Us

I say this because that is simply what it means to be God in Christ. God is the most valuable person in the universe. He is the sum and source of all true pleasure (Psalm 16:11; 37:4). And knowing this in our experience is what triumphs over temptation. Knowing the preciousness of God and the pleasures of his fellowship will strip pornography of its power. We defeat the deceitful pleasures of lust with the superior pleasures of knowing God. Paul said it like this: “I count everything as loss because of the surpassing worth of knowing Christ Jesus my Lord” (Philippians 3:7).

To read or listen to the rest of the sermon, click here: