"Giving up our desire to take revenge is a hard sacrifice, perhaps the hardest, which Christ requires of us. For our whole human nature cries out for vengence against our enemies. The desire for revenge is stronger in our human blood than any other desire. But - and we know it - we can no longer take revenge. If my enemy stands there before my eyes, and I am overcome by the obsession to finally be able to take revenge, then Jesus Christ stands at once behind my enemy and entreats me: do not lift up your hand, but leave vengence to me; I will take it."
- Dietrich Bonhoeffer (1906-1945), Christ's Love and Our Enemies (1938).