Matthew Henry Commentary Revelation 18:1-8

"After these things I saw another angel coming down out of heaven, having great authority; and the earth was lightened with his glory. And he cried with a mighty voice, saying, Fallen, fallen is Babylon the great, and is become a habitation of demons, and a hold of every unclean spirit, and a hold of every unclean and hateful bird. For by the wine of the wrath of her fornication all the nations are fallen; and the kings of the earth committed fornication with her, and the merchants of the earth waxed rich by the power of her wantonness. And I heard another voice from heaven, saying, Come forth, my people, out of her, that ye have no fellowship with her sins, and that ye receive not of her plagues: for her sins have reached even unto heaven, and God hath remembered her iniquities. Render unto her even as she rendered, and double [unto her] the double according to her works: in the cup which she mingled, mingle unto her double. How much soever she glorified herself, and waxed wanton, so much give her of torment and mourning: for she saith in her heart, I sit a queen, and am no widow, and shall in no wise see mourning. Therefore in one day shall her plagues come, death, and mourning, and famine; and she shall be utterly burned with fire; for strong is the Lord God who judged her." — Revelation 18:1-8 (ASV)

The downfall and destruction of the mystical Babylon are determined in the counsels of God. Another angel comes from heaven. This seems to be Christ himself, coming to destroy his enemies, and to spread abroad the light of his gospel through all nations.

The wickedness of this Babylon was very great; she had forsaken the true God, and set up idols, and had drawn all kinds of people into spiritual adultery, and by her wealth and luxury kept them under her influence. The spiritual merchandise, by which multitudes have wickedly lived in wealth from the sins and follies of humankind, seems principally intended.

Fair warning is given to all who expect mercy from God, that they should not only come out of this Babylon but also assist in her destruction. God may have a people even in Babylon. But God's people will be called out of Babylon, and called effectually, while those who share in the sins of wicked people must receive their plagues. (Revelation 18:9–19)