atheist beliefs as there religious beliefs.
Atheists are united only by the fact that they don't believe in any gods - that's a unifying lack of belief and everything else is a free-for-all. There is only one shared theist (religious) belief, which is the belief that there is a god.
Adherents of the Abrahamic faiths share more beliefs, Christians a broader set, Catholics even more specific and so on.
Without a belief system one can't function as a human being.
But those belief systems are atheist, they are compatible with atheism - they do not spring from, but rather alongside, atheism. Some theists, presumably, have beliefs about what are the best sport teams in a given league, but their theism does not turn that position into a theistic belief.
O.