1 Thessalonians 4:1-8

Overview:
 You're doing great, but you need to be doing better (do so more and more) in your walk with God. You need to stand clear of any kind of sexual immorality - be in control of your body and your lusts, that you do not act like the unsaved. God will punish those who disobey this commandment. God doesn't want us to be impure, but pure and holy. Know that if you disregard this, that you are disobeying God, not me.
Application:
If I follow Paul's example, I will point out sin in a fellow believer's life and plead with him to return to a godly pure life. Sometimes it's far easier to ignore the problem than deal with it, but experience says if I do that the problem will grow. Confronting in a loving manner is the order of the day.