In my 1988 sociology class they said one theory is that human social evolution goes from animism, to polytheism and then to monotheism in the end. But my 2000 atheistic teacher said deism (the final scientific stage of monotheism basically) is just another form of atheism. He explained 18th century deists would be atheists today and they were only theists because of the social and legal pressure to believe in at least one god then. So I guess for him it'd be animism, to polytheism, to monotheism to atheism. That was his opinion at least.