Atheism Wars and Religion?

Atheists typically point to religion as the cause of wars. For example, Dawkins does in “The God Delusion.” The believer’s blind faith is said to drive them to kill because he is hoping to please God by promoting His cause. However, they neglect to mention the killing done to promote Atheism such as the Cultural Revolution in China. Christians daily are slaughtered there by Atheists to promote Atheism. Do the moral atrocities in China invalidate the claim that a populous informed by Atheism would be less likely to commit ideology driven crimes against humanity and wars?