One of the earliest monotheistic religions, Atenism was introduced during the 14th century BCE by Pharaoh Amenhotep IV, later known by his adopted name, Akhenaten. After raising the obscure(世に知られていない、不明瞭な)sun god known as Aten to the status of supreme god, Akhenaten declared the solar deity the only god and forbade the worship of all others. Atenism remained Egypt's state religion for approximately 20 years before falling out of favor.