Your glorying is not good. Know you not that a little leaven leavens the whole lump?
All Commentaries on 1 Corinthians 5:6 Go To 1 Corinthians 5
John Chrysostom
AD 407
Paul says that the Corinthians are to blame, because by taking pride in this man they have hindered him from repenting. Here he indicates that the problem is one for the whole church, not just for an individual. This is why he uses the symbol of the leaven, which, although a small thing in itself, transforms the whole lump into its own nature. This man will do the same thing if he is allowed to go unpunished.