The exact meaning of the term here is uncertain. The following are the principal interpretations:
1. The officials known as angels or messengers of the synagogue, transferred to the Christian Church. These were mere clerks or readers; so that their position does not answer to that of the angels presiding over the churches. There is, besides, no trace of the transfer of that office to the Christian Church.
2. Angels proper Heavenly guardians of the churches. This is urged on the ground that the word is constantly used in Revelation of a heavenly being; by reference to the angels of the little ones (Mat_18:10), and to Peter's angel (Act_12:15). It is urged that, if an individual may have a guardian angel, so may a Church. Reference is also made to the tutelar national angels of Dan_10:21; Dan_12:1.
But why should the seer be instructed to write to heavenly messengers, with exhortations to repentance and fidelity, and describing them as "rich," "poor," "lukewarm," etc. (Rev_2:4; Rev_3:1, Rev_3:16)?
3. The angels are a personification of the churches themselves: the Church being spoken of as if concentrated in its angel or messenger. But in Rev_1:20, they are explicitly distinguished from the golden candlesticks, the churches.
4. The rulers ard teachers of the congregation. These are compared by Daniel (Dan_12:3) to stars. See Mal_2:7, where the priest is called the messenger (angel) of the Lord; and Mal_3:1, where the same word is used of the prophet. See also Hag_1:13. Under this interpretation two views are possible.
...(a) The angels are Bishops; the word ἄγγελος sometimes occurring in that sense (as in Jerome and Socrates). This raises the question of the existence of episcopacy towards the close of the first century.
...(b) The word is used of the ministry collectively; the whole board of officers, including both presbyters and deacons, who represented and were responsible for the moral condition of the churches. See Act_20:17, Act_20:28; 1Pe_5:1-5.
Dr. Schaff says: "This phraseology of the Apocalypse already looks towards the idea of episcopacy in its primitive form, that is, to a monarchical concentration of governmental form in one person, bearing a patriarchal relation to the congregation, and responsible in an eminent sense for the spiritual condition of the whole. . . . But even in this case we must insist on an important distinction between the 'angels' of the Book of Revelation and the later diocesan Bishops. For aside from the very limited extent of their charges, as compared with the large territory of most Greek, Roman Catholic, and Anglican Bishops, these angels stood below the Apostles and their legates, and were not yet invested with the great power (particularly the right to confirm and ordain) which fell to the later Bishops after the death of the Apostles. . . . The angels, accordingly, if we are to understand by them single individuals, must be considered as forming the transition from the presbyters of the apostolic age to the Bishops of the second century" ("History of the Apostolic Church").