I wrote to you in my letter not to associate with sexually immoral people — not at all meaning the people of this world who are immoral, or the greedy and swindlers, or idolaters. In that case you would have to leave this world. But now I am writing to you that you must not associate with anyone who claims to be a brother or sister but is sexually immoral or greedy, an idolater or slanderer, a drunkard or swindler. Do not even eat with such people.
What business is it of mine to judge those outside the church? Are you not to judge those inside? God will judge those outside. “Expel the wicked person from among you.”
1 Corinthians 5:9-13 (NIV)