North America. Some North American indian tribes believed in a god, but did
not actively worship it, their philosophy, "Our grandfathers and our great-
grandfathers were won't to contemplate the earth alone, solicitous only
to see whether the plain afford grass and water for their horses. They
never troubled themselves about what went on in the heavens, and who
was the creator and governor of the stars.
James, do you have a source for that statement? That statement flies in the face of everything I know about Native American culture and the history of that culture.
About your opening question : Communism.
Keep in mind that political groups are culturally defined. Political groups and religious groups and social groups are cultural entities.
*edit to add: the question of mythology is a complex one - even 'rational' groups have the need to develop mythology to substantiate and maintain their philosophies. As Georges Bataille said: The greatest contemporary myth is that there is no myth.