An angel is a supernatural being found in many religions, whose duties are to assist and serve God. They typically act as messengers, as believed in the main three monotheistic religions. Angels or Angelology is a branch of theology that deals with a hierarchical system of angel messengers, celestial powers or emanations, and the study of these systems. It primarily relates to kabbalistic Judaism and Christianity, where it is one of the ten major branches of theology, albeit a neglected one.

Most scholars acknowledge that Judeo-Christianity owes a great debt to Zoroastrianism in regard to the introduction of angelology and demonology, as well as Satan (Ahriman) as the ultimate agent of evil. As the Iranian Avestan and Vedic traditions and also other branches of Indo-European mythologies show, the notion of demons had existed long before.

It is believed that Zoroastrianism had an influence on Jewish angelology, and therefore modern Christian angelology, due to the appearance of elements from Zoroastrianism in Judaism following Israel’s extended contact with the Persian Empire while in exile in Babylon, which has led some to believe that Zoroastrianism borrowed these beliefs from Judaism. Borrowed notions may include, the introduction of Satan as a supreme head over the powers of evil (present mainly in Christian and Islamic theology), in contrast to God: comparing Satan to Angra Mainyu (also known as Ahriman) of the Zoroastrian faith, who was the arch-enemy of Ahura Mazda, the supreme Universal God of mankind. Angels, some also believe, may have first been depicted as God’s helpers in Zoroastrianism, and their hierarchy is comparable to modern Angelology’s hierarchy.