Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the Lord. Malachi 4:5.
To prepare a people to stand in the day of God, a great work of reform was to be accomplished [by the Advent Movement]. God saw that many of His professed people were not building for eternity, and in His mercy He was about to send a message of warning to arouse them from their stupor and lead them to make ready for the coming of the Lord.
This warning is brought to view in Revelation 14. Here is a threefold message represented as proclaimed by heavenly beings and immediately followed by the coming of the Son of man to reap “the harvest of the earth.”
The angels are represented as flying in the midst of heaven, proclaiming to the world a message of warning, and having a direct bearing upon the people living in the last days of this earth’s history. No one hears the voice of these angels, for they are a symbol to represent the people of God who are working in harmony with the universe of heaven.
The three angels’ messages are to be combined, giving their threefold light to the world. In the Revelation, John says, “I saw another angel come down from heaven, having great power; and the earth was lightened with his glory.”… This represents the giving of the last and threefold message of warning to the world.
Revelation 18 points to the time when, as the result of rejecting the threefold warning of Revelation 14:6-12, the church will have fully reached the condition foretold by the second angel, and the people of God still in Babylon will be called upon to separate from her communion. This message is the last that will ever be given to the world; and it will accomplish its work. When those that “believed not the truth, but had pleasure in unrighteousness” (2 Thessalonians 2:12), shall be left to receive strong delusion and to believe a lie, then the light of truth will shine upon all whose hearts are open to receive it, and all the children of the Lord that remain in Babylon will heed the call: “Come out of her, my people” (Revelation 18:4).
From “Maranatha”, by Ellen White