The Myth of Atheist Unification
Austin Cline of About.com has written an excellent article exposing the myth that there exists an "atheist movement" which threatens society. Check it out.
The fact that several people share something in common while working for some cause does not entail that whatever they share in common is a belief system, a belief, or is functioning as a belief system. This is obviously true of characteristics which are irrelevant to whatever cause people are working for, like simply being human or having hair, but it's also true of characteristics which are somehow connected to the cause, like being female, being a cancer survivor, or being a business owner.