The great tragedy is not mainly masturbation or fornication or acting like a peeping Tom (or curious Cathy) on the Internet. The tragedy is that Satan uses the guilt of these failures to strip you of every radical dream you ever had, or might have, and in its place give you a happy, safe, secure, American life of superficial pleasures until you die in your lakeside rocking chair, wrinkled and useless, leaving a big fat inheritance to your middle-aged children to confirm them in their worldliness.
He summarizes a vast area of truth in two rather shocking statements: Theology can conquer biology. Justification can conquer fornication. I've never seen it put that way before, but it certainly strikes me as a biblical formulation. Note that he doesn't say "theology will conquer biology," as if victory over sin is automatic. Theology provides the foundation and justification puts in you a position to receive God's life-changing power, but then you must fight and fight hard and keep on fighting, knowing that sometimes you will fail. What then? Either you give in (which is what the advocates of homosexuality support) or you stand and fight in Jesus' name, fighting in the power of the Lord but fighting nonetheless. Piper again:
The distinguishing mark of saving faith is not perfection. The mark of faith is not that I never sin sexually. The mark of faith is that I fight. I fight anything that dims my sight of Jesus as my glorious Savior. I fight anything that diminishes the fullness of the lordship of Jesus in my life. I fight anything that threatens to replace Jesus as the supreme Treasure of my life. Anything that stands between me and receiving Jesus. Faith fights -- not with fists or knives or guns or bombs, but with the truth of Christ.
I met a man, a good man, a godly man, a man who truly loves the Lord who told me of his struggle with homosexual temptation. He is far advanced in years. He told me that when he was in his fifties, he thought here would come a time when he was no longer tempted. But, he said, it is not so. By God's grace, he has not given in for almost sixty years. Yet he fights the battle daily. I said he is a good man and I mean that. Fighting sin -- and sometimes falling (and we all fall and fail in many ways) -- is not a mark of unbelief. Fighting hard and ending up bruised and bloody is a sign that you have been in the arena for the Lord. Those who give in and then make excuses are in much worse condition.
I will not quote from the end of the sermon because I do not want to spoil it for you except to say he actually tells young people what to say on the morning after sexual failure. Here is preaching that mixes strong theology with gritty realism about the temptations and failures we all experience. John Piper points the way out of despair to lasting hope in Christ. This is great preaching, and I am happy to commend it to you.