In the fifth year of his reign, he changed his name from Amenhotep IV, meaning "Amun is satisfied". He did this because he left Egypt's traditional polytheism. He founded a monotheistic worship of the Egyptian sun god, Aten. He destroyed the temples of Amun. His new religion was called Atenism. It was the first known attempt at monotheism in the world. Naturally, this made enemies of the many priests of the old religion. 