What is the issue here?

First, chapter 6 is a bridge between chapters 5 & 7, between immorality and marriage.

The primary issue is taking brothers to court in malice. (Not in reference to mere legal proceedings such as insurance matters etc.)

v3
Judge Angels?
Rev 20:1,7-10; Jude v6

James 4:1-3

v6-7
Why not suffer being defrauded instead of winning a case at the expense of the cause of Christ.