Romans 12:19-21 (New International Reader's Version)
19 My friends, don't try to get even. Leave room for God to show his anger. It is written, "I am the One who judges people. I will pay them back,"—(Deuteronomy 32:35) says the Lord. 20 Do just the opposite. Scripture says, "If your enemies are hungry, give them food to eat. If they are thirsty, give them something to drink. By doing those things, you will pile up burning coals on their heads." —(Proverbs 25:21,22)
21 Don't let evil overcome you. Overcome evil by doing good.
Much is said in the Bible about how Christians should treat others. When you give your life to Jesus Christ and determine that you will follow and serve Him, you are no longer your own. You have been bought with a price, the price of Jesus' death on the cross for your sins. The great thing is that as God's possession, He takes on the task of righting every wrong that has been done to us. He promises to take care of any evil that is done to you.
That gives us the freedom to show the love and mercy of Jesus Christ to everyone we encounter, especially those who choose to harm us. It is our responsible to show those and all in the world the true nature and character of God. By our humble example, leaving room for God to correct anything that is done, we can help to make the good news of Christ and example for even evil people to follow.
There have been many examples of the love of Christians turning the evil hand of those who chose to harm. Leave the judgment and vengeance to God. We will be called to account for displaying the proper character of God to others.