Part of Atheism is just a believe there there is no teleological force directing humanity/nature.
Personally I don't necessarily think atheism is a case of "absence" or "nothingness" so much as seeing consciousness as an illusion (we have less control of even ourselves/perceptions than we realize so a definitive spiritual presence or soul seems far fetched) and assuming what we are and will be always has been in a raw material way (law of conservation of mass - matter is not created or destroyed, just transformed).
As an atheist, I think the best explanation I've ever hear of religion is that you "just have to have faith." Understanding the concept of blind faith is a riddle because at some level we have to just believe in something, even if it's science or absence of higher spiritual beings, because no one can know everything but determining what to place faith in can seem random at times so I prefer to find experiences and observations that guide me.
Also, if there is a higher being I don't understand the requirement for worship and following some specific religious laws set down by this entity - there's no reason to think a God would nurture humanity alone or care to direct us socially. For this reason a lot of established religion feels more like an attempt at culture and social control than some honest self actualization.
Leucius: ...I can see why you'd be appalled at so called "religious" people and what they do and have done throughout the course of history, and I can see why you'd rather not believe than to believe in a God that people have done inexcusable things in the name of...
This suggests atheism/agnosticism is a willful turning away from a known God or refusal to acknowledge a higher power in spite for human nature. That's never been my understanding of atheism.