Extracts and comments from Revelation Chp. 14:6
And I saw another angel flying in midst of Heaven having (a)an everlasting gospel (b)to (c)preach unto them that dwell on the Earth, and to (d)every Nation, and kindred, and tongue and people.
(a) This angel sent specially to deliver a message. It is important to note that an angelic messenger used. A human agent at this stage would not be heard. An angelic agent cannot be stopped, as is evidenced in Daniel 9:23 & 10:11-19. Also, an angelic agent cannot be corrupted, who has not given allegiance to Satan.
The A.V. translates "an" as "the", which would give the impression that its message is the same as that of Christ to Israel, Paul to Israel first, and then the Gentiles, and that of Christendom today, with its many (corrupted) variations. All of the above "Gospels" (messages) are different, with Paul's latter "Gospel" (which was corrupted by Constantine, and Helena his mother), confirmed by (or re-discovered by) Martin Luther 1200-1300 years later; being that Salvation is by Grace only at this moment in time.
These points are made to show that the word "Gospel", does not always mean that of Salvation by Grace, but means a firm, truthful, unchangeable set of information, from, in this case Jehovah Zebaoth. The Interlinear Strongs no. 2098 means "news", "declare", "bring", "show", and often in the context of God's Word was "Good News". In this case the message is "Everlasting", and is to all them that dwell on the Earth.