Perhaps it is true that certain violent remedies employed against tyrants have put an end to certain forms of evil, but they have not eliminated evil. Evil itself will take root elsewhere, as we have seen through history. The fertilizer that stimulates its growth is yesterday’s violence. Even “just wars” and “legitimate defense” bring vengeance in their train. Fresh crimes invariably ensue.…But the future of the person who turns to God is not determined by the past, and therefore neither is the future of humanity. God’s forgiveness creates the possibility of an entirely new future. The cross breaks the cycle of violence.

Source: Jesus and the Nonviolent Revolution