There have been 3 response to war and vioence in the history of the Christian Church...

1) Pacifism - the ethics and praxis of Jesus and the church for the first 300 years (still pursued by the anarcho-christians such as Catholic Worker communities in the U.S., Bruderhof, Quakers).
2) The Just War theory (a relativst ethic that was developed by Augustine, which is presently tha mainstream teaching, (it was developed after yje Roman Emperor Constantine legalised and patronised the church attempting to make it decorative to empire.
3) The Crusdade mentality (indiscriminate "Christ and No Quarter" killing, Hiroshima etc) the theology and praxis of Bush and the Christian Right.

Another bunch of Christian anarcho pacifists presently before the courts for resisting the ear on Iraq. This time in the Australian outback. Their trial kicks off Oct 3rd.
www.pinegap6.org

Also check out the plowshares movement....
www.plowsharesactions.org