I want to call your attention to an excellent post by Mason over at the New Ways Forward blog. He has done a great job of pointing out why, despite the violent language of Revelation, it is not justifying or encouraging violence on the part of believers. He points out that the violence in Revelation is all done either by the evil powers, the Beast, etc., or else by God in effecting justice on those who oppose him. . .and NEVER by the people of God.
Right judgment and wrath for wrongdoing is only to be placed in the hands of God. A Christian doctrine of nonviolence is based not on the idea that evil is really not such a big deal, so violence is an overreaction, but rather on the fact that evil is an incredibly big deal and that fallen humanity simply can not use violence and justice together without our sinful natures twisting the violence into injustice, vengeance, and in doing so pushing along the endless spiral of violence.