"Atheist" feels like such a strange and artificial category, lumping people together on the basis of what they don't believe rather than what they do.
It's a bit like defining everyone who isn't Indo-European or Asiatic as "black", even though there's more genetic diversity in Africa than the rest of the world put together.
> "Atheist" feels like such a strange and artificial category
Bah, not any more that any other category: I have religious friends who are in theory from the same religion: some believe in heaven some don't, some believe in the miracles some don't, etc..
But yes, there can be atheists who believe that the earth is flat or that crystals can heal, etc.
But they all identify with the same hierarchical structure to some degree, at least if we're talking about a group like Roman Catholics, Sunni Muslims etc. It gets more complicated of course where e.g. Judaism is concerned, because that's more than just a religion.
It's a bit like defining everyone who isn't Indo-European or Asiatic as "black", even though there's more genetic diversity in Africa than the rest of the world put together.