Then I saw another angel flying in the midst of heaven, having the everlasting gospel to preach to those who dwell on the earth—to every nation, tribe, tongue, and people—saying with a loud voice, “Fear God and give glory to Him, for the hour of His judgment has come; and worship Him who made heaven and earth, the sea and springs of water.” (Re 14:6–7)
He refers to the messenger who runs throughout the church, which is spread far and wide and is to be extended even more. He uses the singular for the plural, or in the one [messenger] he is suggesting the unity of the single church; yet, at the same time, he is alluding to the preachers of eternal life. It rightly says that he preaches an eternal gospel, by which the preacher is taught to look forward to eternal salvation. And so the one who preaches is indicated by that which is preached. Therefore the psalm says, “He who makes the winds his messengers and burning fire his ministers.”
Although from the beginning of the Christian faith we have learned that the kingdom of heaven is said to be approaching, here, however, he proclaims that the hour of His judgment will come very soon and is virtually here already. And therefore he maintains that preaching of this kind must necessarily be made known to all people, as also the Lord said, “This gospel will be preached throughout the world, and then the end will come.” And to show that that moment of time takes place, when the adversity of the last persecution will draw near, he has rather added that the temporal power of the beast should best be regarded as insignificant and that the Lord rather be feared, whom every one of his creatures, whom he mentions, acknowledges to be eternal.
Primasius of Hadrumetum, Commentary on the Apocalypse 14.6–7