Atheist Amazonian tribe.

[CapnAwesome]

Depends on how you define 'god'. Zeus, for example, was not omnipotent, but he was still considered a god.
Yes, it depends how you define god, and I think that a spirit being which lives above the clouds and sometimes gives commands to humans would fall within most atheists' definition of god.

If that's the case Christianity is a polytheistic religion, as that fits the definition of angels. Satan would also be a God. Are you basically admitting that you believe in more than one God, or are you just niggling to try to prove a point? There is a difference between Atheism and naturalism, most western Atheists are naturalists, most eastern philosophies are Atheist but not naturalists.