Faith--believing things with no proof for no reason other than that the believer wants them to be true--leads inevitably to atrocity.
While I can't disagree with your point in general, I don't think that "inevitably" is quite accurate. I have yet to see the Quakers or the Unitarians commit violence. My impression of Buddhism is that it is quite peaceable. Still, you are right in too many instances. I know of no instances in which atheists killed for their (non) beliefs.
