1 Corinthians 5:6–13

6 Your boasting is not good. Do you not know that a little leaven leavens the whole lump? 7 Cleanse out the old leaven that you may be a new lump, as you really are unleavened. For Christ, our Passover lamb, has been sacrificed. 8 Let us therefore celebrate the festival, not with the old leaven, the leaven of malice and evil, but with the unleavened bread of sincerity and truth.

9 I wrote to you in my letter not to associate with sexually immoral people—10 not at all meaning the sexually immoral of this world, or the greedy and swindlers, or idolaters, since then you would need to go out of the world. 11 But now I am writing to you not to associate with anyone who bears the name of brother if he is guilty of sexual immorality or greed, or is an idolater, reviler, drunkard, or swindler—not even to eat with such a one. 12 For what have I to do with judging outsiders? Is it not those inside the church whom you are to judge? 13 God judges those outside. “Purge the evil person from among you.”

(ESV)