1 Corinthians 5:2

And ye are puffed up, and have not rather mourned, that he that hath done this deed might be taken away from among you (KJV)

Then: Adding to the odiousness, Corinthians laugh. They are prideful and see no sin in the act(s) of one among them. Fee points out the difficulties of Corinthians' attitudes towards sexual conduct (p. 196). Their carry-over gentile beliefs restricted the value of marriage to a need for legal heirs, approved the presence of mistresses for social events, and endorsed obtaining concubines for physical utility. Fee doesn't mention that the acceptance of women as equal inheritors of the kingdom of God was a long time coming. Rather he concentrates on Paul's disgust with pride as formerly condemned in 4:18-29 (p. 194) and the issue of church authority. The sin is horrid, but still worse are the problems it reveals - including disdain of apostolic guidance through the authority of Christ.

Now: Writing or thinking about Paul's comments regarding incest is depressing. It's a hidden sin of the modern age: People doing wrong because they have the power over a minor, because their desires overcome inner consciences, because... because... because. Paul's method of discipline is to reject the malefactor according to the Old Testament law in Leviticus 18:24-30 and 20:22-24 (Baker, p. 80).

Extra Source: The First Epistle to the Corinthians by Gordon D. Fee (Eerdman's 1987) online at http://books.google.com/books?id=XlBp10nUTXAC&dq=Gordon+Fee+Bible+commentator&printsec=frontcover&source=in&hl=en&ei=SwLNSu3nA4v6Mf2XlDo&sa=X&oi=book_result&ct=result&resnum=12#v=onepage&q=&f=false
Cornerstone Biblical Commentary 1 Corinthians (William Baker), 2 Corinthians (Ralph Martin & Carl Toney), ed. by Philip Comfort. Carol Stream: Tyndale House Publishers, c2006.