Revelation 18:8; For Strong is the Lord God Who Judgeth Her
Revelation 18:8 Therefore shall her plagues come in one day, death, and mourning, and famine; and she shall be utterly burned with fire: for strong is the Lord God who judgeth her.
John uses the Old Testament as his source. There he reads that God said to Babylon: Both [the loss of children and widowhood) will overtake you in a moment, on a single day (Isaiah 47:9; see Jeremiah 50:31).
Isaiah 47:9 But these two things shall come to thee in a moment in one day, the loss of children, and widowhood: they shall come upon thee in their perfection for the multitude of thy sorceries, and for the great abundance of thine enchantments.
Jeremiah 50:31 Behold, I am against thee, O thou most proud, saith the Lord GOD of hosts: for thy day is come, the time that I will visit thee.
Her buildings and earthly possessions will be burned by fire, and the people will not even “save themselves from the power of the flame” (Isaiah 47:14). Suddenly, the depopulated city lies in ruins, and Babylon is left as a lonely, forsaken figure.
All this has taken place because of God’s judgment against her. John describes the Lord God as mighty, which in this case is unique. A few times in the Apocalypse (Revelation 5:2; 10:1; 18:21) angels have been called mighty, and so have political and military leaders (Revelation 6:15; 19:18).
Revelation 5:2 And I saw a strong angel proclaiming with a loud voice, Who is worthy to open the book, and to loose the seals thereof?
Revelation 10:1 And I saw another mighty angel come down from heaven, clothed with a cloud: and a rainbow was upon his head, and his face was as it were the sun, and his feet as pillars of fire:
Revelation 18:21 And a mighty angel took up a stone like a great millstone, and cast it into the sea, saying, Thus with violence shall that great city Babylon be thrown down, and shall be found no more at all.
Revelation 6:15 And the kings of the earth, and the great men, and the rich men, and the chief captains, and the mighty men, and every bondman, and every free man, hid themselves in the dens and in the rocks of the mountains;
Revelation 19:18 That ye may eat the flesh of kings, and the flesh of captains, and the flesh of mighty men, and the flesh of horses, and of them that sit on them, and the flesh of all men, both free and bond, both small and great.
John P. M. Sweet notes that this mighty city of Babylon (v10, 18) “is no match for the might of God.” When the hour of judgment has come, there is no escape from the wrath of God. As the writer of the Epistle to the Hebrews observes, “It is a fearful thing to fall into the hands of the living God” (Heb. 10:31).
Kistemaker, S. J., & Hendriksen, W. (1953–2001). Exposition of the Book of Revelation (Vol. 20, p. 492). Grand Rapids: Baker Book House.