The Greek word aggelos means ‘messenger’ and as such angels are described as bearing messages from God to the patriarchs (e.g. Gen. 22: 11). In the later (post-exilic) literature (perhaps influenced by contact with Zoroastrianism) angels are regarded as supernatural beings organized before God in a hierarchy (e.g. Dan. 7: 10; 9: 21). Against them are ranged evil angels under Satan (Matt. 25: 41). Unlike the more conservative Sadducees, the Pharisees encouraged these developed beliefs (Acts 23: 9), which were needed to complement a doctrine of God's absolute transcendence. From the time of the book of Daniel (2nd cent. BCE) angels are given names (Dan. 8: 16; 10: 13) and specific tasks. In the book of Tobit the angel Raphael is indispensable to the story's climax. In the gospels they are available to assist Jesus (Matt. 4: 11) and to be personal representatives of children before the Father (Matt. 18: 10). The devil also has a troop of angelic assistants (Matt. 25: 41).
In several epistles (e.g. 1 Pet. 3: 22) the redemptive work of Christ is interpreted in terms of his triumph over supernatural celestial beings who may be angels. So also Paul in Col. 2: 8–15. The writers of the NT inhabited a different thought-world from us, but Paul's essential affirmation is that the Law, which Jews believed was given to Israel by the mediation of angels, has been superseded and Christ's authority established.