‘Dare any of you, having a matter against a fellow Christian, go to law before the unrighteous and not before those who are holy (‘the saints')?'
‘Having a matter.' The use of the middle voice might suggest a hint of selfishness, ‘having their own matter'.
Paul's point here is that Christians see things differently from others. ‘Dare any of you - ?.' This suggests that while pagan judges might be perfectly fair and reasonable, they might not see things from a Christian perspective. To go before them was a risk both morally and socially. ‘The unrighteous'. Such judges or magistrates are not subject to God's Law nor are they aware of what is right in Christian eyes, and indeed in God's eyes. ‘Those who are holy'. This refers to the godly in the church. They look at things from God's viewpoint. Surely, he is saying, it is better to be judged by those set apart to God, those who see things from God's point of view.
We can compare how Rabbis warned against taking such matters before non-Jews, because Gentiles lacked the Jew's high moral perspective. They also had in mind, among other things, the discrimination that might be revealed against them.