Satan started his false church and empire in ancient Babylon (now called Iran/Iraq). From there came such abominations as the first "virgin birth" reported in religion. (On Dec. 25th btw), most all pagan idol worship, mother worship, and fertility worship, to name just a few.

Reading the Old Testament Bible you can see the Babylonian culture was always the enemy enslaving and slaughtering the Israelites.

When Jesus Christ came on the scene, preached, died, and resurrected starting the Christian movement, Babylonian religious beliefs slowly merged, and eventually became known as the Universal Church, aka the Catholic church. Hence the Mary idolatry, the fertility festivals of Christ-mass, and Ishtar (Easter), Saint idolatry, and the most abominable worship of a man called "The Vicar of Christ". aka Pope idolatry.

Not only is Satan, Antichrist and False Prophet the antithesis to the Holy Trinity of:  God The Father, Jesus The Son, and The Holy Ghost, so also is his  "geographical trinity". Satan's reconstituted empires will be located in Babylon (Iran/Iraq) as his commercial headquarters. Rome (The Vatican) as his political headquarters, and Jerusalem as his religious headquarters.  Click here for more info.

The first to see Jerusalem in Revelation's Babylon were the French Jesuit Jean Hardouin (1646-1729) and the French Calvinist Firmin Abauzit (1679-1767). Abauzit suggests that the "seven mountains" in Rev 17:9 are the seven hills on which Jerusalem stands and the "fall of Babylon" in Rev 18 is the fall and destruction of Jerusalem in 70 AD.

Several Old Testament prophets referred to Jerusalem as being a spiritual harlot and a mother of such harlotry (Isaiah 1:21; Jeremiah 2:20; Jeremiah 3:1-11; Ezekiel 16:1-43; Ezekiel 23). Some of the these Old Testament prophecies as well as the warnings in the New Testament concerning Jerusalem are in fact very close to the text concerning Babylon in Revelation, suggesting that John may well have actually been citing those prophecies in his description of Babylon.

For example, in Matthew 23:34-37 and Luke 11:47-51, Jesus himself assigned all of the bloodguilt for the killing of the prophets and of the saints (of all time) to the Pharisees of Jerusalem, and, in Revelation 17:6 and 18:20,24, almost identical phrasing is used in charging that very same bloodguilt to Babylon. This is also bolstered by Jesus' statement that "it's not possible for a prophet to be killed outside of Jerusalem." (Luke 13:33, see also Rev 11:8).

In Jeremiah 13, Judah is warned that because of her whoredom, the cups of all of the people will be "filled with wine," they will be "made drunk," and the nation will be suddenly destroyed. This is identical to the scenario in Revelation 17-18; it also correlates with the warning of Jesus that Jerusalem would be suddenly invaded and destroyed just prior to his return to earth in Luke 21:20-22. So, according to this view, John's prophecy about Babylon was merely a detailed repetition of warnings already given by many Old Testament prophets and by Jesus himself in Matthew 23:37-38 and Luke 19:41-44.

According to this view, "the great city, Babylon" in Rev. 17:18 which is also "the great city where their Lord was crucified" in Rev 11:8, the earthly Jerusalem is opposed (cf. Acts 8:1, 1 Thes. 2:14-16, Gal 4:22-31, Rev. 2:9-10,3:9) to the spiritual, heavenly, new Jerusalem, which is the Christian Church of the faithful of Jesus (the bride): "And I John saw the holy city, new Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband." (Rev 21:2)

The scholars who defend this position believe that earthly Jerusalem "riding the seven-headed beast" refers to Jerusalem being controlled and subjected to the overlordship of the scarlet beast Rome in the 1st century (cf John 19:15). Some see it as an evil relationship between the harlot, apostate Jerusalem, and the scarlet beast Rome on whom she is seated to crucify Jesus and persecute the Christians. This evil alliance is confirmed in the Book of Acts (Acts 4:26-28, 12:1-3). The beast Rome later hated the harlot Jerusalem and burned her with fire in 70 AD. (see also abomination of desolation)
“ And the ten horns which you saw, and the beast, these will hate the harlot and will make her desolate and naked, and will eat her flesh and will burn her up with fire. ”

— Rev 17:16 NASB

Roman Catholic Church
Main article: Whore of Babylon (historicism)

Historicist interpreters commonly used the phrase "Whore of Babylon" to refer to the Roman Catholic Church. Most Reformation writers and all Reformers themselves, from Martin Luther (who wrote On the Babylonian Captivity of the Church), John Calvin, and John Knox (who wrote The First Blast of the Trumpet Against the Monstrous Regiment of Women) accepted this association. The "drunkenness with the blood of saints and martyrs," by this interpretation, refers to the inquisition and the veneration of saints and relics and the Sunday sacredness, were viewed by Reformers as idolatry and apostasy. This interpretation continues to be taught in churches arising from the Adventist movement and it is kept alive by contemporary figures such as Ian Paisley and Jack Chick.

The Catholic Church denies the claim that it is being referred to by the Book of Revelation as the Whore of Babylon. Catholic apologists argue that in Rev 17:10, it states that the seven heads of the Beast are seven mountains on which the woman is seated; they are also seven kings, five of whom have fallen, one is, the other has not yet come, and when he comes he must remain only a little while" (Rev. 17:9–10). ." If five of these kings had fallen in John’s day and one of them was still in existence, then the Whore must have existed in John’s day. Yet the Vatican City did not even exist at that time. Of course they conveniently forget that John's revelation was describing events 2000+ in the future.

William Blake (1809) The Whore of Babylon