As a conservative, you may be the exception, but I suspect that it wasn't the spreading of atheism that resulted in so much murder. It was the spreading of the State as God - something many misinterpret as atheism. All too often, many "atheists" are the most extreme religious zealots that exist. Their religion is either Anti-Christian or Pro-State, not a mere lack of belief. Most self proclaimed "atheists" are certainly not void of religion - they are just too stupid and misguided to realize it.
Yes, your religionist argument there is so brilliant.