1After this, I saw four angels standing at the four corners of the earth, holding the four winds of the earth, so that no wind would blow on the earth, or on the sea, or on any tree. 2I saw another angel ascend from the sunrise, having the seal of the living God. He cried with a loud voice to the four angels to whom it was given to harm the earth and the sea, 3saying, “Don’t harm the earth, the sea, or the trees, until we have sealed the bondservants of our God on their foreheads!” 4I heard the number of those who were sealed, one hundred forty-four thousand, sealed out of every tribe of the children of Israel:
5of the tribe of Judah twelve thousand were sealed,
of the tribe of Reuben twelve thousand,
of the tribe of Gad twelve thousand,
6of the tribe of Asher twelve thousand,
of the tribe of Naphtali twelve thousand,
of the tribe of Manasseh twelve thousand,
7of the tribe of Simeon twelve thousand,
of the tribe of Levi twelve thousand,
of the tribe of Issachar twelve thousand,
8of the tribe of Zebulun twelve thousand,
of the tribe of Joseph twelve thousand, and
of the tribe of Benjamin twelve thousand were sealed.
9After these things I looked, and behold, a great multitude which no man could count, out of every nation and of all tribes, peoples, and languages, standing before the throne and before the Lamb, dressed in white robes, with palm branches in their hands. 10They cried with a loud voice, saying, “Salvation be to our God, who sits on the throne, and to the Lamb!”
11All the angels were standing around the throne, the elders, and the four living creatures; and they fell on their faces before his throne, and worshiped God, 12saying, “Amen! Blessing, glory, wisdom, thanksgiving, honor, power, and might, be to our God forever and ever! Amen.”
13One of the elders answered, saying to me, “These who are arrayed in the white robes, who are they, and where did they come from?”
14I told him, “My lord, you know.”
He said to me, “These are those who came out of the great suffering. They washed their robes and made them white in the Lamb’s blood. 15Therefore they are before the throne of God, and they serve him day and night in his temple. He who sits on the throne will spread his tabernacle over them. 16They will never be hungry or thirsty any more. The sun won’t beat on them, nor any heat; 17for the Lamb who is in the middle of the throne shepherds them and leads them to springs of life-giving waters. And God will wipe away every tear from their eyes.”
We see the terminology of a "great multitude" here in Revelation 19, and also in Revelation 7. In the latter, John's reference is plain, that this large group of people refers to the saved of earth, the first reference in chapter 7 to the saved from the people of Israel (Rev 7:4f), and secondly to all groups of people on the earth who have been saved by every tribe and kind of people upon the earth who suffered during the tribulation (7:7, 13, 14). These are different from the bride who was rescued in the rapture with the coming of the bridegroom and come back with Him after the destruction of the Beast, False Prophet, evil kingdoms, and religious groups during this time.
The response of the multitude of heaven and the elders, and creatures around the throne was praise to God for judging the harlot. This is the same multitude praising God in 7:9 when the 144,000 were first introduced and the multitudes of their converts were revealed. All the saints in heaven are included in this multitude. Some see this as angels praising God. However, the things they praise God for are more appropriate to saints than angels. The injunction of 18:20 is fulfilled here. A fourfold praise is directed toward God. The reasons for praising God are listed as well by the multitude. God has judged and avenged.
Blood is a figurative way of saying the murders of the saints. “God’s servants” refers to the apostles and prophets as a minimum, but more likely includes all martyred believers of all time (OT and NT saints).
Babylon’s smoke rising forever may mean that it will burn eternally, or it could be a figurative way of saying its destruction will be total. The city will experience eternal destruction and punishment from God. The city could also represent its residents, and this would then refer to the destiny of Babylon’s inhabitants, their eternal torment in the lake of fire.