Revelation 18:1

The downfall and destruction of Babylon form an event so fully determined in the counsels of God, and of such consequence to his interests and glory, that the visions and predictions concerning it are repeated. 1. Here is another angel sent from heaven, attended with great power and lustre, Rev 18:1. He had not only light in himself, to discern the truth of his own prediction, but to inform and enlighten the world about that great event; and not only light to discern it, but power to accomplish it. 2. This angel publishes the fall of Babylon, as a thing already come to pass; and this he does with a mighty strong voice, that all might hear the cry, and might see how well this angel was pleased to be the messenger of such tidings. Here seems to be an allusion to the prediction of the fall of pagan Babylon (Isa 21:9), where the word is repeated as it is here: has fallen, has fallen. Some have thought a double fall is hereby intended, first her apostasy, and then her ruin; and they think the words immediately following favour their opinion; She has become the habitation of devils, and the hold of every foul spirit, and the cage of every unclean and hateful bird, Rev 18:2.

— Matthew Henry's Concise Commentary (public domain)