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

[Existentialist]

I think it is perfectly justifiable, if wrong, to say Atheism is an ideology or belief system.

A rather ambiguous statement. I think you need to be clearer in what you're saying, it seems a little slippery to say something is "justifiable, but wrong". I think it's a matter of opinion. Some people obviously think that atheism is an ideology or belief system, some people think it isn't. Both sets of people think the other side is wrong and should adopt their definition. I have my views, others have theirs. If this situation is accepted, the debate can continue.