It’s hard to be considered part of something when the whole point of your belief lacks the major criteria that everyone else in the category possesses.
Most times you see atheism compared to any other set of beliefs the monikers “religious” and “not religious” are used. I would say that atheism is technically not a religion, but the community acts in such similar ways to religious groups that it’s hard to not just put them all in one bubble. I don’t really see people as religious or not religious anymore, I just know they have an opinion about it.
