1 Corinthians 6
New International Version (NIV)
Lawsuits Among Believers
6 If any of you has a dispute with another, do you dare to take it before the ungodly for judgment instead of before the Lord’s people? 2 Or do you not know that the Lord’s people will judge the world? And if you are to judge the world, are you not competent to judge trivial cases? 3 Do you not know that we will judge angels? How much more the things of this life! 4 Therefore, if you have disputes about such matters, do you ask for a ruling from those whose way of life is scorned in the church? 5 I say this to shame you. Is it possible that there is nobody among you wise enough to judge a dispute between believers? 6 But instead, one brother takes another to court—and this in front of unbelievers!
7 The very fact that you have lawsuits among you means you have been completely defeated already. Why not rather be wronged? Why not rather be cheated? 8 Instead, you yourselves cheat and do wrong, and you do this to your brothers and sisters. 9 Or do you not know that wrongdoers will not inherit the kingdom of God? Do not be deceived: Neither the sexually immoral nor idolaters nor adulterers nor men who have sex with men[a] 10 nor thieves nor the greedy nor drunkards nor slanderers nor swindlers will inherit the kingdom of God. 11 And that is what some of you were. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God.
--
Eye for Eye
38 “You have heard that it was said, ‘Eye for eye, and tooth for tooth.’[h] 39 But I tell you, do not resist an evil person. If anyone slaps you on the right cheek, turn to them the other cheek also. 40 And if anyone wants to sue you and take your shirt, hand over your coat as well. 41 If anyone forces you to go one mile, go with them two miles. 42 Give to the one who asks you, and do not turn away from the one who wants to borrow from you.
Love for Enemies
43 “You have heard that it was said, ‘Love your neighbor[i] and hate your enemy.’ 44 But I tell you, love your enemies and pray for those who persecute you, 45 that you may be children of your Father in heaven. He causes his sun to rise on the evil and the good, and sends rain on the righteous and the unrighteous. 46 If you love those who love you, what reward will you get? Are not even the tax collectors doing that? 47 And if you greet only your own people, what are you doing more than others? Do not even pagans do that? 48 Be perfect, therefore, as your heavenly Father is perfect.
--
Though he is free to do as he wishes, the most godly thing to do in many cases is allow God to judge this fellow in the end and send him a note of forgiveness, etc. God will make all things right in the end.