Bad Arguments: "A Religion of Peace"

No religion is a "religion of peace" if it has a long history of war-like activity. You can't take the peaceful parts of it and say that that is what it represents. If its adherents are war-like over several centuries, if various sects of the religion wage holy war against one another, etc... I'm not talking about conflicts like WW I, in which a lot of the participants just happened to be adherents of a few of the major monotheistic religions, but about the Crusades and other conflicts in the name of religion.

Actually though, the fact that Christianity did nothing to stop secular wars, in societies where almost everyone was ostensibly Christian, is also pretty damning.

Your religion is a religion of peace, when you happen to be at peace, and a religion of war when you are at war. Religion is orthogonal to war and peace. That, in a way, is more terrifying than anything. Think of a French Catholic shooting against a German Catholic in the trenches of the Great War. Their religion simply makes no difference at all in this situation.