Ah, but we're not talking about religious belief. We're talking about religion. Language is such a fun thing isn't it? The two are not interchangeable. Les brought up religion, not religious belief. And if you look at the dictionary definition (dictionary.com), this is part of the definition... " a set of beliefs concerning the cause, nature, and purpose of the universe, " it carries on to say 'especially' as it applies to religious belief, but, it does not say exclusively as it applies to religious belief.
As for the rest of your post Niflmir... not all religious are alike, not all atheists are alike. That's a bit of a no brainer. But you don't sign off your posts about atheism being a non-specific belief, with an invitation for me to join your atheist organization with its set mandate of how you all view the world. :lol:
But certainly you must see how that definition is incomplete. Physics is not a religion, but it certainly defines a set of beliefs concerning the cause, nature and... ok not the purpose of the universe. And I think that is the point. Maybe the definition is fine after all.
What lacks in atheism is purpose. We do not presuppose it. An atheist does not believe that there is necessarily a purpose to the universe. One can say that buddhists are atheist because they believe in no god, but they are certainly religious.
This is one of the various arguments that the religious have against the atheists: life without meaning. In some sense that is the very definition of atheism, the disbelief of god given purpose in the universe. Instead we must find our purpose in a celebration of life. In choosing some principle to lead our life by. In trying very hard to better those people around us. But it is not something one can believe to be inherent to the universe.