1 Thes. 4:1-8 (ESV)
Finally, then, brothers, we ask and urge you in the Lord Jesus, that as you received from us how you ought to live and to please God, just as you are doing, that you do so more and more.  For you know what instructions we gave you through the Lord Jesus.  For this is the will of God, your sanctification: that you abstain from sexual immorality;  that each one of you know how to control his own body in holiness and honor,  not in the passion of lust like the Gentiles who do not know God;  that no one transgress and wrong his brother in this matter, because the Lord is an avenger in all these things, as we told you beforehand and solemnly warned you.  For God has not called us for impurity, but in holiness.  Therefore whoever disregards this, disregards not man but God, who gives his Holy Spirit to you.
Paul here addresses the Thessalonians about living the sanctified life. It must be emphasized here that this is not about progressing in sanctification, but living in sanctification. We do not progress in sanctification each time we successfully resist the temptation to sexual immorality. But we do jeopardize our sanctification when we succumb to temptation. Our sanctification is a matter of keeping the name of God, the name that was given to us in Baptism, the name that sanctified us in Baptism, holy among us. Now His name is holy in and of itself. But we pray in the Lord’s Prayer that it would be kept holy among us. That it would not be profaned among us, and treated as profane. To profane something means to take something that is Holy and sacred and defile it. We are holy and sacred by the fact that God has given us his holy name. And just as our actions in public reflect on our family name, even more so our actions in public reflect on the name that God has given us and what we think of it. One way to profane the name of God, is here spoken, it is to act as if it did not belong to us, as if we were not made holy by it. It is to go along with the gentile way of life and treat our bodies as they do, even more so as if we were nothing but animals without self control.
Of course this is exactly the message the world would relay to us today. I am astounded by how often the teaching of abstinence in schools is greeted with hostility by people who think so little of the teenagers as to imply that they are animals incapable of self control. For sure, those who have succumbed to the temptation ought not be treated as second class, maligned, and scorned. Far from it. They ought to be forgiven. They ought to be cared for. More often than not this sort of activity outside of wedlock brings on guilt, and shame even among those who are not Christian. People know when they have been used. Yet Christ has died for all and forgiven all. Christian don’t lose the holy name of God that was given them in baptism because they have succumbed to the temptation of sexual immorality. But they are guilty of profaning that name. Only in forgiveness will they be restored, and made whole again. The desecrated are washed of the profane and restored to their holy place in forgiveness alone.