John Piper rarely gets starker than he does in the following quote. His biblical remedy for lust? Well, it's simple really. Understand that unless you are one of those who fights lust with all your heart, you were never truly saved. The quote begins with a question from someone who heard one of his sermons:

“Are you saying then that a person can lose his salvation?” In other words, if Jesus used the threat of hell to warn about the seriousness of lust, does that mean that a Christian can perish?

This is exactly the same response I got a few years ago when I confronted a man about the adultery he was living in. I tried to understand his situation and I pled with him to return to his wife. Then I said, “You know, Jesus says that if you don’t fight this sin with the kind of seriousness that is willing to gouge out your own eye, you will go to hell and suffer there forever.” As a professing Christian he looked at me in utter disbelief, as though he had never heard anything like this in his life, and said, “You mean you think a person can lose his salvation?”

So I have learned again and again from firsthand experience that there are many professing Christians who have a view of salvation that disconnects it from real life, and that nullifies the threats of the Bible, and puts the sinning person who claims to be a Christian beyond the reach of biblical warnings. I believe this view of the Christian life is comforting thousands who are on the broad way that leads to destruction (Matthew 7:13). Jesus said, if you don’t fight lust, you won’t go to heaven. Not that saints always succeed. The issue is that we resolve to fight, not that we succeed flawlessly . . . if we don’t fight lust we lose our soul. The apostle Peter said, “Abstain from fleshly lusts that wage war against the soul (1 Peter 2:11).” The stakes in this war are infinitely higher than in any threat of World War III. The apostle Paul listed “immorality, impurity, passion, evil desire, and greed,” then said, “it is on account of these things that the wrath of God will come” (Colossians 3:6). And the wrath of God is immeasurably more fearful than the wrath of all the nations put together. In Galatians 5:19 Paul mentions immorality, impurity and sensuality and says, “Those who practice such things shall not inherit the kingdom of God” (Galatians 5:21).

John Piper, Future Grace (Sisters, OR: Multnomah Publishers, 1995), 331. Available electronically from Logos Bible Software.