  The general rejection of war has a long history that parallels the just war tradition and its idea that wars should be fought for the sake of peace and justice. In the West, pacifism and the just war tradition have roots in both Christian and non-Christian sources. For Christian thinkers, one of the primary problems is trying to reconcile the pacific commandments of Jesus with the apparent moral necessity of using war to defend the innocent. This problem is acute for Christians since Jesus seems to advocate an ethic of nonviolence both in the Sermon on the Mount and in his submission to violence, while Augustine and others use both Biblical sources (such as Paul’s letter to the Romans) and natural law to argue in favor of the just war idea. In the European tradition, pacifism is an ideal that develops alongside of and in contrast to the just war tradition, with adherents of pacifism including the Mennonites and Quakers, as well as Christian humanists such as Erasmus.