You know how the feelings are: "I'm going to get even. I'm going to get the better of him." But Jesus said, "No. Be so generous and sacrificing that you will bless those who curse you, do good to those who hate you, and pray for those who spitefully use and persecute you." Now, look at this qualification.
We already have an example. God generously gives to those who hate Him. We will not go through the whole thing, but it is good to note that Jesus reaches a conclusion that is rather startling. Why should we be this way? The answer is simple: Because that is the way God is! It is that simple. IF we want to be a son of God, THEN we have to emulate Him.