1 Corinthians 5:9-13
I wrote you in my earlier letter that you shouldn't make yourselves at home among the sexually promiscuous. I didn't mean that you should have nothing at all to do with outsiders of that sort. Or with crooks, whether blue or white-collar.
Or with spiritual phonies, for that matter. You'd have to leave the world entirely to do that! But I am saying that you shouldn't act as if everything is just fine when a friend who claims to be a Christian is promiscuous or crooked, is flip with God or rude to friends, gets drunk or becomes greedy and predatory.
You can't just go along with this, treating it as acceptable behavior. I'm not responsible for what the outsiders do, but don't we have some responsibility for those within our community of believers? God decides on the outsiders, but we need to decide when our brothers and sisters are out of line and, if necessary, clean house.