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

[Entropist]

I could answer your question, but I would be telling you what my belief system is - what my atheism means to me. I could go on quite a long time, I would talk about what the existence of God means in terms of perpetuating capitalism and how the non-existence of God spells major problems for all hierarchies including atheist-labelled ones, and how the absence of a supreme being puts us individually in a position of complete freedom. I could go on a long time about this.

But you are talking about Marxism and existentialism, not atheism.