1 Corinthians 5:6-13

6Your glorying is not good. Know ye not that a little leaven leaveneth the whole lump? 7Purge out the old leaven, that ye may be a new lump, even as ye are unleavened. For our passover also hath been sacrificed, even Christ: 8wherefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth.

9I wrote unto you in my epistle to have no company with fornicators; 10not at all meaning with the fornicators of this world, or with the covetous and extortioners, or with idolaters; for then must ye needs go out of the world: 11but as it is, I wrote unto you not to keep company, if any man that is named a brother be a fornicator, or covetous, or an idolater, or a reviler, or a drunkard, or an extortioner; with such a one no, not to eat. 12For what have I to do with judging them that are without? Do not ye judge them that are within? 13But them that are without God judgeth. Put away the wicked man from among yourselves.