5:9. I wrote to you in an epistle not to keep company with fornicators.
5:10. I mean not with the fornicators of this world or with the covetous or the extortioners or the servers of idols: otherwise you must needs go out of this world.
5:11. But now I have written to you, not to keep company, if any man that is named a brother be a fornicator or covetous or a server of idols or a railer or a drunkard or an extortioner: with such a one, not so much as to eat.
5:12. For what have I to do to judge them that are without? Do not you judge them that are within?
5:13. For them that are without, God will judge. Put away the evil one from among yourselves.
1 Corinthians Chapter 6
He blames them for going to law before unbelievers. Of sins that exclude from the kingdom of heaven. The evil of fornication.
6:1. Dare any of you, having a matter against another, go to be judged before the unjust: and not before the saints?
6:2. Know you not that the saints shall judge this world? And if the world shall be judged by you, are you unworthy to judge the smallest matters?
6:3. Know you not that we shall judge angels? How much more things of this world?