Let me introduce an example of atheism which is not at all a beliefs system : that of scientists (or an important part of them). The existence or non-existence of God is a matter of fact or fantasy, and not a belief for them. Many scientists are religious,but they will never establish a base for search, in any kind of faith, be it the main religions, or mythology or paganism.
This position does not qualify them for stating which beliefs are true and which are not, they simply remain neutral, and keeping an eye in facts. At the same time you will find a great, deep sense of humanism in them. (I adhere to that position as much as I try to humbly follow the philosophy of Jesus, though not in any church, but that´s a personal opinion.)
Un abrazo - Andrés