"destruction of the flesh" - 1 Corinthians 5:5

To deliver such an one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus (KJV)

Then: Paul finishes the prescription of needed discipline and explains his reasons. Delivered to Satan, perhaps the transgressor who will have to endure many afflictions without the presence of the Lord, will recognize the difference and return to the Lord's saving grace. In the day of judgement, he will stand forgiven. "Destruction of the flesh" refers to the destruction of impulses which still control the heart of this believer. As long as he stayed within the congregation, accepted as a fellow-believer, it wasn't likely that he'd ever realize the disconnect between his fleshly actions and the Lord's design for the eternal souls of his followers.

Now: Church outsiders laugh and scorn. Barring anyone from fellowship and communion seems useless. On the other hand, they carefully choose which groups, organizations, or institutions to join according to prestige and reputation. They ignore the comparative aspect involved. Fee (p. 197, 213) reviews the effect on the church. Gentiles brought easy attitudes towards sex into the Corinthian church and, contrary to Paul's high ethical standards, were now exalting "spiritual" tolerance. That mindset could destroy the salvation message by summarily extinguishing a major difference between the church and pagan temples. Paul had to exert his authority to teach both the church and the transgressor. Members should mourn the sinner whose actions were contaminating the whole church. Putting him outside of it could speed the church's recovery and underline the importance of high ethical attitudes. Unfortunately, the effect is limited in today's age when people can just go to another church down the street.

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