In the Sermon on the Mount, Jesus said, "Blessed are the peacemakers: for they shall be called the children of God." To work for peace, you must have a peaceful heart. When you do, you are the child of God. But many who work for peace are not at peace. They still have anger and frustration, and their work is not really peaceful. We cannot say that they are touching the Kingdom of God. To preserve peace, our hearts must be at peace with the world, with our brothers and sisters. When we try to overcome evil with evil, we are not working for peace. If you say, "Saddam Hussein is evil. We have to prevent him from continuing to be evil," and if you then use the same means he has been using, you are exactly like him. Trying to overcome evil with evil is not the way to make peace.
Jesus also said, "Thou shalt not kill; and whosoever shall kill shall be in danger of the judgment. But I say unto you, that whosoever is angry with his brother without a cause shall be in danger of the judgment ... whosoever shall say, 'Thou fool,' shall be in danger of hell fire." Jesus did not say that if you are angry with your brother, you will be put in a place called hell. He said that if you are angry with your brother, you are already in hell. Anger is hell. He also said that you don't need to kill with your body to be put in jail. You only need to kill in your mind and you are already there.