Jamieson, Fausset and Brown on Revelation 18:24

24. Applied by Christ (Mt 23:35) to apostate Jerusalem, which proves that not merely the literal city Rome, and the Church of Rome (though the chief representative of the apostasy), but the WHOLE of the faithless Church of both the Old and New Testament is meant by Babylon the harlot; just as the whole Church (Old and New Testament) is meant by "the woman" (Re 12:1). As to literal city, Aringhus in Bengel says, Pagan Rome was the "general shambles" for slaying the sheep of Jesus. Fred. Seyler in Bengel calculates that papal Rome, between A.D. 1540 and 1580, slew more than nine hundred thousand Protestants. Three reasons for the harlot's downfall are given: (1) The worldly greatness of her merchants, which was due to unholy traffic in spiritual things. (2) Her sorceries, or juggling tricks, in which the false prophet that ministers to the beast in its last form shall exceed her; compare "sorcerers" (Re 21:8; 22:15), specially mentioned among those doomed to the lake of fire. (3) Her persecution of (Old Testament) "prophets" and (New Testament) "saints."