“Do not take revenge, my friends, but leave room for God’s wrath, for it is written: “It is mine to avenge; I will repay,” says the Lord.” Romans 12:19
Sometimes a person might hurt us by saying or doing something mean to us. When that happens, we often want to “get them back.” We want to make them hurt even worse so they will know not to be mean to us again. This is not the attitude a Christian should have.
Paul told the Romans that we should not avenge ourselves. To avenge is to do evil to someone because they have done evil to us. God reminds us that He will punish all evil at the day of judgment. Instead of getting mad (“giving place to wrath”), the one who loves God must show kindness to the person doing wrong. In the next verse, Paul says to feed your enemy if he is hungry. By doing good you make him feel bad for being mean to you. Even if he does not feel guilty, you will have done the right thing and God will punish the person if he does not repent.
Ultimately, we want the person to repent and serve God. When he repents, he will feel sorry for any wrongs. We should help him turn from his meanness, not return hatred for hatred.