Romans 12:21

Be not overcome of evil. The infliction of vengeance is a sign, not of strength, but of weakness. The one who allows his temper to be stirred up and his Christian principles of love and self-control to be abandoned suffers defeat. But the person who represses the desire for revenge and turns a wrong done to him into an opportunity for showing kindness gains a victory over himself and over the powers of evil. This is not only nobler in itself but will be much more effective. It may disarm an enemy (cf. Proverbs 15:1) and win another soul. Thus God has not meted out to sinners the vengeance they have long deserved, but rather has overwhelmed them with love and mercy. And it is the goodness, forbearance, and long-suffering of God that lead men to repentance (Romans 2:4). The Christian who is being transformed into the image of God (Romans 12:2) will show by his treatment of his enemies that day by day his character is becoming more and more like the character of God, who is love (1 John 4:8).