Adam Clarke on 1 Corinthians 5:11

But now I have written - I not only write this, but I add more: if any one who is called a brother, i.e. professes the Christian religion, be a fornicator, covetous, idolater, railer, drunkard, or extortioner, not even to eat with such - have no communion with such a one, in things either sacred or civil. You may transact your worldly concerns with a person that knows not God, and makes no profession of Christianity, whatever his moral character may be; but ye must not even thus far acknowledge a man professing Christianity, who is scandalous in his conduct. Let him have this extra mark of your abhorrence of all sin; and let the world see that the Church of God does not tolerate iniquity.