Nazi Germany was mostly catholic and was condoned by the pope at the time.
And you clearly haven't read the countless deaths and persecution caused by religious secterian power and dogmas and their resulting wars.
Your entire appeal is a red herring. Violence is born out of bad developmental psycho-social environments and has nothing to do with Atheism vs Belief.
Also, I'm not an atheist per se. I'm agnostic which is an entirely different ball of wax and something you might want to look into.
Also, since you're clueless about the role of attachment relationships in the development of emotional self-regulation and how poor emotional self-regulation is the foundation of violent and abherent behaviors, may I suggest you read Allan N Schore's extensive work in bringing attachment theory to new heights of understanding. There are a few others, but his work is one of the most cited.