Participation in warfare is now so fully a part of the majority Christian heritage that it is hard for most Christians to imagine anything else. Catholics and Protestants of all the major denominations hold to the theory which justifies Christian participation in warfare.
In holding to this theory, the vast majority of Christians have followed Augustine, a bishop in north Africa at the beginning of the fifth century. They have developed an informal system for determining when it is justified and necessary for Christians to kill other human beings. Following this line of reasoning, Christians have participated in revolutions, wars of national defense, wars of conquest and genocide, wars of religious intolerance, and wars caused by mistakes and misunderstandings.
At the same time, however, small numbers of Christians have refused to kill other human beings. They have based this on the demands of the gospel of Jesus Christ, who laid down his own life instead of punishing the enemies of his people. These Christians continue to believe that prayer and selfless obedience to God's way of peace and love have a greater influence on the final outcome of events than do bullets and bombs.
Some trust in chariots and some in horses,
But we trust in the name of the Lord our God.
(Psalm 20:7, NIV)