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atenism

n. A monotheistic religion of ancient Egypt.

Wikipedia
Atenism

Atenism, or the Amarna heresy, refers to the religious changes associated with the eighteenth dynasty Pharaoh Amenhotep IV, better known under his adopted name, Akhenaten. In the 14th century BC, Atenism was Egypt's state religion for around 20 years, before subsequent rulers returned to the traditional gods and the Pharaohs associated with Atenism were erased from Egyptian records.