When and where did atheism first start ?

[Belacqua]

There were probably early humans witnessing the first inventions of gods that were like "WTF?" They were probably strictly empiricists.

 I suspect you're half joking here, but you do bring up some solid questions. 

There's no way to know, but we can make some educated guesses about how "the first inventions of the gods" came about. I don't think it's likely it looked like the cartoon version that's easiest to imagine. Here's Ogg hearing the thunder, and somebody asks him, in English, "what causes that, Ogg?" and he says, "It must be a god." And some people believe him and some don't. That scenario contains so many modern concepts that early humans couldn't even think it.

Granted, all animals are empiricists at some level. My cats learn where not to sit, through experience. Even the earliest humans would know not to hit their thumbs. They might well connect weather conditions with more effective hunting, and things like that. And since they live very much in the concrete world of cause and effect, they are likely to assume that effects for which they don't know the cause in fact have one, somewhere. 

It's also likely that early humans would attribute more consciousness to objects than we do. They might assume that animals have desires similar to humans, that the weather has some sense of what it wants, that certain plants or landscape features need to be kept happy. This is still the case in animist groups. So it's not like some wise guy invented a god one day in order to trick people. Human beings think through symbols and metaphors, when they think of anything more than the most concrete relations, so it seems to me a kind of default state for people to have notions of non-human consciousnesses, emotions not located inside people, powers that it helps us to satisfy. 

If people want to claim that objects without the capacity for conceptual thought are atheists, that's fine with me. Dirt is atheist. The space inside an empty box is atheist. But human beings who have begun to conceptualize the world and make an effort to improve their lives within it will probably come up with vague god-like concepts from pretty early on. Granted, from those fuzzy ideas to the Christian Trinity is a huge jump and maybe not a good one. But in terms of thinking about the world in terms of non-human spirits, that seems likely to be pretty much the default to me.