[Porsche-O-Phile]

Well, it sort of has to be. You can't pin it on a non-existent thing. An atheist (by definition) has no religious belief. As such, it's a bit difficult to blame any action of theirs on such a belief (since it doesn't exist). Maybe academic, but I'd say the argument that Stalin killed religious people as a matter of political gain is probably more likely than "because" he happened to be an atheist. There's a distinction.