Monotheism is the belief in one all-powerful, all-encompassing deity. Many modern religions practice it, however, polytheism is a more ancient tradition. The first monotheistic state was Egypt under Pharaoh Akhenaten, who instituted the worship of Aten, displacing the entire previous pantheon. However, his changes were reversed upon his death.
Judaism later emerged as a monotheistic religion, from which Christianity and Islam then emerged. Other monotheistic religions include Zoroastroanism, Sikhism and the Bahá'í Faith. Some monotheistic religions have a deity and his antagonist, such as God and Satan, or Ahura Mazda and Angra Mainyu.