“Beloved, never avenge yourselves, but leave it to the wrath of God, for it is written, “Vengeance is mine, I will repay, says the Lord.”” -Romans 12:19
Paul appeals tenderly to the believers, calling them Beloved. Certainly, it is a sensitive charge. Human nature wants to retaliate, seek what we, in our limited view, believe will serve justice. But Paul warns the believers that it is not their place. Vengeance belongs to God, the omniscient, all-wise judge of the universe.
Paul is not suggesting there will be no retribution to those who sin against us. He assures there is a place for the wrath of God and we can be certain God will judge the wicked.
One way to look at this is to leave vengeance to the professional, commending the injustice done to us to God’s care. That way we are free to live out God’s will for us, trusting he will do better than we could ever do at meeting out justice properly and satisfactorily against those who sin against us.