The Everlasting Gospel
Notice Revelation 14:6 pictures an angel preaching the everlasting Gospel. There has and always will be only one Gospel. People do not get saved different ways in different ages.
Rev 14:6 And I saw another angel fly in the midst of heaven, having the everlasting gospel to preach unto them that dwell on the earth, and to every nation, and kindred, and tongue, and people,
Rev 14:7 Saying with a loud voice, Fear God, and give glory to him; for the hour of his judgment is come: and worship him that made heaven, and earth, and the sea, and the fountains of waters.