v1-3: The Lamb on the earth, Zech 14.4. In contrast to the second beast (13.11), this is the Lamb (NIV margin). He has taken away our sins (John 1.29), and now reigns supreme.
The servants of God have the Father's name written on their foreheads, in contrast to the number of man, 13.16-18. Here is an assurance of their belonging to God. Here is also a clear distinction with those who do not know God.
v4-5: The 144,000, who are redeemed from the earth, and faithful to the Lamb, enduring the persecution of the dragon and the beast. Here are the first fruits, and others must follow.
v6-7: The everlasting gospel, Matt 24.14; Mark 13.10. "Fear God and give Him glory … worship Him," for "the hour of judgment has come." It seems that those who hear the message reject it; all bear personal responsibility, for all hear.
v8: Babylon, the centre of the power of the antichrist, is destroyed. Although Babylon is called "the great," it is not the greatest, for God's power is greater. She deceived the nations, enjoying widespread influence in the world.
v9-10: The third angel brings judgment upon those who worship the beast and receive his mark, as in 13.15-17. Either people have the mark of the Father, or the mark of the beast; there is no third option, no fence-sitting. The wrath of God is "full strength," or 'without mixture,' thus there is no mercy, for they have rejected the God of mercy. See also Ps 75.8, and compare Num 5.15.
v11: There is torment forever, there is no rest, for those who received the mark of the beast. The torment from God is without intermission, like a never-ending "stream of burning sulphur" (Is 30.33). The torment is "for ever and ever," marking an emphasis, which we must not ignore. See 9.6 for a foretaste, on earth, of this awful experience.
Whilst we may balk at such torment, a man's unbelief is rejection of Jesus Christ; and a man's sins are offences against Almighty God. The seriousness of these things reflects the greatness of the God who is offended and rejected.
v12: There remain the saints of God, who must stand firm and be faithful.
v13: See also 12.17; 13.7; followers of Jesus Christ are killed. But they have their hope in Christ, they are "blessed" and they enjoy "rest."
v14-16: The harvest of salvation, directed by the Son of Man. He is Lord of the harvest, Matt 9.37-38, and here He demonstrates His authority.
v17-20: The harvest of judgment, by the angel; a distressing and disturbing image. For the Christian in the age of grace, this must motivate us to godly living, and more effective witness and evangelism.