Atheism is defined as disbelief in God (weak atheism), or as the doctrine or belief that there is no God (strong atheism). Agnosticism is the belief that only material things can be known, and hence that knowledge of God, or anything supernatural, cannot be certain. Theists, of course, come in a variety of delusional ilks.
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Eine Kleine Nattermusing
Science of Evolution
The Scarlet A