Is it true that atheism has killed more people then organized religion?...

[Existentialist]

... atheism itself has not killed anyone. There are no atheists who have killed people due to their atheism.

These are two separate and mutually exclusive statements. I'll take them separately. "Atheism has not killed anyone" - this is only true because only people can kill (ie murder) anyone. Ideas don't kill people. Therefore, theism has never killed, nor can atheism. Next, "There are no atheists who have killed people due to their atheism" - people who kill ostensibly for religious reasons do so because their political or ideological position has led to them feeling that their victim is so bad or so evil that they deserve to die. I can't think of any religion that ever taught people to kill just because the religion said so. Usually it requires an interim step to determine that the person being killed is deserving of death. The thing is, the atheists are vulnerable to the same thought process, aren't they? ("Islam is evil - muslims deserve to die"). So in my view, religious believers don't kill people because of their religion. Atheists don't kill people because of their atheism. But religion and atheism can both contribute to a thought process that leads to a killing. In the case of atheists, this is less likely to be very well documented, hence the lack of evidence, and as soon as they become a killer their motives are more likely to be attributed to something else like racism or a psychotic episode. However there are a huge an increasing number of attacks on muslims due to their religion, and some members of the EDL have declared themselves to be atheists. Personally I think the conditions are in place for a killing by an atheist, attributed to their atheism, to take place, it's only a matter of time, and actually I'd be surprised if it hasn't happened already. Of course, when it does happen, the responsibility for it falls entirely on the killer. For anyone to blame their religion or their atheism is lame, so your statement will hold true, just as it holds true for religious believers: the killer is the killer, not the religion, not the atheism, so it is a bit of a meaningless statement that doesn't prove anything.