That is what Josh Moody says about I Corinthians 5 and the man having his father's wife.
We actually had a Bible study about this chapter today while a respite worker tended to Dave. Yes, I said "sex" around my 12-year old son and younger daughter. It is in the Bible. Things seemed to be going a little slow in the study until my wife paraphrased the situation of the Corinthians' boasting and tolerating the blatant sin for my five-year old girl. That broke it open like a sack of grain.
What I believe we need to understand from this chapter is that God is very serious about sin. Church discipline is a real deal. And the attitude the Corinthians should have had toward this man is something like: "Ok, you are out of our protection, and back to the world you love so much. But we pray that having come up against your sin, as rubbed in by being in Satan's playground, you will repent, and join us in heaven forever." But for now, you are out. The Church is more important than endorsing your corrupt lifestyle." Pretty psychologically incorrect, huh.
What is the message for those not particularly involved in blatant sin? Don't go there. God wields a mighty sword. And we do not want to be found as Satan's victims under God's sovereign control. But the way to avoid it is not to get all white-knuckled and resist with will-power. It is to stay on the narrow road fenced in by the justice of God on one side, and the mercy and grace of the Passover Lamb, Christ, on the other.
Being at a good church, then, is not a religious ritual, it is the very place where the help to stay on this path lies.