An angel (Greek: angelos, "messenger") is a celestial being believed to function as a messenger or agent of God in CHRISTIANITY, ISLAM, JUDAISM, and ZOROASTRIANISM. In the Near Eastern antecedents to Judaism, angels were often understood to be gods or lesser divinities. Their existence was taken for granted by the biblical authors. The use of the word angel may have been a way of describing what was believed to be an appearance of God himself in human form.
In the Old Testament, angels are called "messengers," "men," "powers," "princes," "sons of God," and the "heavenly host." They either have no body or one that is only apparent. They come as God's messengers to aid or punish, are assigned to individual persons or nations, and often have a name (Michael, Gabriel, Raphael, Uriel). New Testament statements about angels reflect Jewish views of these beings. Angels, for example, announced Christ's birth (Luke 2) and resurrection (Matt. 28).
Ancient and medieval peoples widely accepted the influence of good spirits, or angels, and evil spirits, or fallen angels (see DEMON; SATAN). During the Middle Ages, theologians developed a hierarchy of angels. They were classified in the following nine ranks (beginning with the lowest): angels, archangels, principalities, powers, virtues, dominations, thrones, cherubim, and seraphim. Angels are a popular subject in folklore, literature, and art.