On the Angels of the Churches

St. John in the Apocalypse is shown seven candlesticks and in their midst, the Son of Man holding seven stars (Rev. 1:13, 20). The candlesticks represent the seven Churches of Asia; the stars, the angels of those Churches. He is bidden to write to the respective angels  of those Churches and distribute to each his meed of praise or blame. Origen (Hom., xiii in Luc., and Hom., xx in Num.) explains that these are the guardian angels of the Churches, a view upheld by Dean Alford. But St. Epiphanius (Hær., xxv) explicitly rejects this view, and, in accordance with the imagery of the passage, explains it of the bishops. The comparison of a teacher to a star is quite Scriptural: And they that be wise shall shine as the brightness of the firmament; and they that turn many to righteousness as the stars for ever and ever. (Daniel 12:3). St. Augustine’s reason for interpreting angels of the Churches as the prelates of the church is that St. John speaks of them as falling from their first charity which is not true of the angels. (Catholic Encyclopedia)

St. Ephrem the Syrian ca. 306-373
In his degree the priest is an angel, but in his doings a man. By mercy he is made a mediator, between God and mankind. (Homily on Admonition and Repentance 11)
St. Ambrose of Milan ca. 339-397
You saw there the deacon, you saw the priest, you saw the chief priest [i.e. the bishop]. Consider not the bodily forms, but the grace of the Mysteries. You spoke in the presence of the angels, as it is written: For the priest’s lips keep knowledge, and they seek the law at his mouth, for he is the angel of the Lord Almighty. Mal.2:7 There is no place for deception nor for denial. He is an angel who proclaims the kingdom of Christ and eternal life. He is to be esteemed by you not according to his appearance, but according to his office. Consider what he delivered, reflect upon the rule of life he gave you, recognize his position. (On the Mysteries 2.6)
Blessed Augustine ca. 354-430
[In] the Apocalypse of John we read: Unto the angel of the Church of Ephesus write: These things says He that holds the seven stars in His right hand, who walks in the midst of the seven golden candlesticks; I know your works, and your labour, and your patience, and how you can not bear them which are evil: and you have tried them which say they are apostles, and are not, and hast found them liars: and hast borne, and hast patience, and for My name’s sake hast tolerated them, and hast not fainted. (Rev. 2:1-3) Now, if He wished this to be understood as addressed to a celestial angel, and not to those invested with authority in the Church, He would not go on to say: Nevertheless I have somewhat against you, because you have left your first love. Remember therefore from whence you are fallen, and repent, and do the first works; or else I will come unto you quickly, and will remove your candlestick out of his place, unless you repent. Revelation 2:4-5 This could not be said to the heavenly angels, who retain their love unchanged, as the only beings of their order that have departed and fallen from their love are the devil and his angels. The first love here alluded to is that which was proved in their tolerating for Christ’s name’s sake the false apostles. To this He commands them to return, and to do their first works. Now we are reproached with the crimes of bad men, not done by us, but by others; and some of them, moreover, not known to us. Nevertheless, even if they were actually committed, and that under our own eyes, and we bore with them for the sake of unity, letting the tares alone on account of the wheat, whosoever with open heart receives the Holy Scriptures would pronounce us not only free from blame, but worthy of no small praise. (Letter 43 Chap. 8.22)
St. Dionysius the Areopagite ca. 5th cent.
But you will find that the Word of God calls gods, both the Heavenly Beings above us, and the most beloved of God, and holy men amongst us, although the Divine Hiddenness is transcendently elevated and established above all, and no created Being can. properly and wholly be said to be like unto It, except those intellectual and rational Beings who are entirely and wholly turned to Its Oneness as far as possible, and who elevate themselves incessantly to Its Divine illuminations, as far as attainable, by their imitation of God, if I may so speak, according to their power, and are deemed worthy of the same divine name. (Celestial Hierarchy Chap. 12 Section 3)
St. Gregory the Dialogist ca. 540-604

But because Holy Scripture is frequently accustomed to designate the preachers of the Church, by the name of ‘Angels’ because they announce the glory ofthe heavenly country, we can in this place understand ‘Angels’ to mean holy preachers. For this cause it is that John, in the Apocalypse, writing to the seven Churches, speaks to the Angels of the Churches, that is, to the preachers of the peoples. (Morals 34.7[14], LF 31:629)

Bede the Venerable ca. 673-735
Rev 1:20 The mystery of the seven stars which you saw in My right hand, and the seven golden lampstands: The seven stars are the angels of the seven churches, and the seven lampstands which you saw are the seven churches.
That is, the rulers of the Church. For the priest, as Malachi says “is the angel of the Lord of hosts” (Mal. 2:7) (Commentary on the Apocalypse)
Rev 3:1-4 “And to the angel of the church in Sardis write, ‘These things says He that has the seven Spirits of God and the seven stars: “I know your works, that you have a name, that you live, and you are dead. Be watchful, and keep that which remains, which you were about to cast out, for I have not found your works perfect before My God. Remember therefore how you have received and heard, and hold fast, and repent. Therefore if you will not watch, I will come upon you like a thief, and by no means shall you know what hour I will come upon you. You have a few names in Sardis who have not defiled their garments; and they will walk with Me in white, because they are worthy.
He reproves this angel, that is, the bishop, as not sufficiently diligent in correcting the bad. He commends him, however, as having some who walk in white, and the name Sardis agrees with these, as that of a precious stone. (Commentary on the Apocalypse)