That's an interesting set of claims. Every one at odds with my understanding and experience. Care to expand on how atheism is a belief system, shares symbols, and has organized congregations?
Perhaps it would clarify my position for me to say that atheism is to me no more a religion than monotheism or polytheism are religions. There are many things you could claim to be religions that fall into one of those 3 categories, but the category itself is not a religion. (Some belief systems fall into more than one, for instance wicca arguably falls into all three.)
If you have concrete evidence to the contrary, I'd be interested in hearing it.
Cheers,
Ben