Paul is astonished that the Corinthians have not dealt with sexual immorality “that is not tolerated even among the pagans” (v1). Paul calls for drastic discipline for two reasons “so that (the immoral man’s) spirit may be saved” (v5) and because the sin affects the community – “a little leaven leavens the whole lump” (v6). Paul makes a clear statement that while we dissociate from a member of our community in unrepentant, gross sin – we do not separate from sinful people in the world. (v10)
It is easy to judge those outside of the faith and ignore the sin in our lives. Indignation against the world’s sin can become an excuse for us to not deal with our own.