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?
6:4. If therefore you have judgments of things pertaining to this world, set them to judge who are the most despised in the church.
6:5. I speak to your shame. Is it so that there is not among you any one wise man that is able to judge between his brethren?
6:6. But brother goeth to law with brother: and that before unbelievers.
6:7. Already indeed there is plainly a fault among you, that you have law suits one with another. Why do you not rather take wrong? Why do you not rather suffer yourselves to be defrauded?
A fault… Lawsuits can hardly ever be without a fault, on the one side or the other; and oftentimes on both sides.
6:8. But you do wrong and defraud: and that to your brethren.