Are the great spiritual teachings really advocating that we fight evil because we are on the side of light, the side of peace? Are they telling us to fight against that other 'undesirable' side, the bad and the black. That is a big question. If there is wisdom in the sacred teachings, there should not be any war. As long as a person is involved with warfare, trying to defend or attack, then his action is not sacred; it is mundane, dualistic, a battlefield situation.