This is an interesting read Christ alone.
History of Atheism
Although the term atheism originated in the sixteenth century – based on Ancient Greek ?θεος "godless, denying the gods, ungodly" [1] – and open admission to positive atheism in modern times was not made earlier than in the late eighteenth century, atheistic ideas and beliefs, as well as their political influence, have a more expansive history.
The spontaneous proposition that there may be no deities at all is logically as old as theism itself (and the proposition that there may be no deity as old as the beginnings of monotheism or henotheism). Philosophical atheist thought appears in Europe and Asia from the sixth or fifth century BCE.
Will Durant explains that certain pygmy tribes found in Africa were observed to have no identifiable cults or rites. There were no totems, no deities, and no spirits. Their dead were buried without special ceremonies or accompanying items and received no further attention. They even appeared to lack simple superstitions, according to travelers' reports. [citation needed] The Vedahs of Ceylon [clarification needed] only admitted the possibility that deities might exist, but went no further. Neither prayers nor sacrifices were suggested in any way [citation needed] .
http://en.wikipedia.org/wiki/History_of_atheism