In view of that great day the Word of God calls upon His people to seek His face with repentance: GrH_c 39.3
“The day of the Lord cometh, for it is nigh at hand.” “Sanctify a fast, call a solemn assembly: gather the people, sanctify the congregation, assemble the elders, gather the children:... Let the priests, the ministers of the Lord, weep between the porch and the altar.” “Turn ye even to me with all your heart, and with fasting, and with weeping, and with mourning: And rend your heart, and not your garments, and turn unto the Lord your God: for he is gracious and merciful, slow to anger, and of great kindness.” Joel 2:1, 15-17, 12, 13. GrH_c 39.4
To prepare a people to stand in the day of God, a great work of reform was to be accomplished. In His mercy He was about to send a message to arouse His professed people and lead them to make ready for the coming of the Lord. GrH_c 39.5
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 prophet saw an angel flying “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 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.” Revelation 14:6, 7. GrH_c 39.6
This message is a part of “the everlasting gospel.” The work of preaching has been entrusted to men. Holy angels direct, but the actual proclamation of the gospel is performed by the servants of Christ on earth.*For a more detailed account of this message and of those who began to proclaim it, see The Great Controversy, chapters 17 and 18, and subsequent chapters that develop the issues further. GrH_c 40.1