How could Joseph ever forgive his brothers for selling him into slavery and telling his father that he was dead? How powerful must that love be to break through the walls of hatred we can build around our hearts? Jesus tells us that we must love, do good to, bless, and pray for those that hate us. It is that love called agapao, the love that is wholly unmotivated by any hope of return, that we are expected to show for those that despise us. That's the point of it all: We are loving not to save their souls, but ours. Once we love like that, fully and wholly with the love God has for us, there is no turning back.
The Scripture references are Genesis 45:3-11, 15, Psalm 37:1-9, and 1 Corinthians 15:35-38, 42-50. The Gospel reference is Luke6:27-38.