A person who disbelieves or lacks belief in the existence of God or gods.
From French athéiste, ultimately from Greek atheos meaning 'without god' (a- 'without' + theos 'god'). The term was initially used as an accusation against those who denied the official gods of the state in ancient Greece.
The word 'atheist' was once such a serious accusation that even early Christians were called atheists by Romans for rejecting the traditional pantheon. Today's distinction between 'atheist' and 'agnostic' was largely popularized by biologist Thomas Huxley in the 1870s.
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