I don't see how Bob would qualify as an atheist. To me atheism implies logical thought, even if only a negative position. An atheist does not believe in god as they have found the arguments invalid, the evidence unacceptable and lacking. Bob does not even have the ability to look at either, as he is not aware of them. I don't think a rock is an atheist for the same reason. The former we call ignorant, the latter incapable.
I actually wonder if Bob was brainwashed as a Catholic, would that actually make him Catholic? I would say that indoctrination, conditioning, etc don't really make someone that religion, just a caricature of it.