A more radical definition that I have heard of, is about the disappearance of (the belief in) powerful but quite alien non-human beings. But then that's much ol

A more radical definition that I have heard of, is about the disappearance of (the belief in) powerful but quite alien non-human beings. But then that's much older than the current atheism : something that monotheistic religions started a long time ago already with their "exclusivity".