Pacifism
From dKosopedia
Pacifism is commitment to opposing war, and usually means holding the beliefs that war is immoral and ultimately counterproductive. A pacifist is a person who believes that war is fundamentally wrong and that it is not a means which should be used to achieve political objectives no matter how good they may be. Many religious and philosophical traditions are pacifist. The original Christian community was pacifist until it gained state power over the Roman Empire. When that happened it succumbed to the temptations of power by violently repressing other religious and philosophical traditions and waging war against non-Christian polities. Following the collapse of the Western Roman Empire the various Christianized barbarian kingdoms in the West waged war against one another and against Islamic and pagan polities.
Pacifism is a tradition of some but not all Roman Catholic religious orders. Among protestants, the Quakers or Society of Friends are pacifist as are the Amish, Mennonites and Church of the Brethren.