Rev 17:5
5 And upon her forehead was a name written, MYSTERY, BABYLON THE GREAT, THE MOTHER OF HARLOTS AND ABOMINATIONS OF THE EARTH.
KJV
John in a vision saw a woman sitting upon a scarlet colored beast, having seven heads and ten horns.
Haters of the Roman Church like to say that's about the Catholic Church and a pope. It is not. It is about a certain "great city" at the end of this world. It is about the city of Jerusalem.
Rev 17:18
18 And the woman which thou sawest is that great city, which reigneth over the kings of the earth.
KJV
Those kings is about the ten kings that manifest with the beast king for the end of this world, which we read about in the Revelation 17:8-13 verses. That also parallels what is written in Daniel 7 about the ten horns which represent ten kings, with a little horn coming up among them to subdue 3 of them.
We are also shown the "seven heads" represent "seven mountains", which are about regions of the earth (not seven hills around Rome). Rev.13:1-8 reveals the beast kingdom will involve power over ALL nations and peoples. The "woman" which is a "great city", NOT A RELIGION or SECT, represents the controlling city over the whole beast kingdom. That is Jerusalem.
Where do you think God will send His two witnesses for the end to prophesy against that beast? To its center of control, Jerusalem...
Rev 11:3-8
3 And I will give power unto my two witnesses, and they shall prophesy a thousand two hundred and threescore days, clothed in sackcloth.
4 These are the two olive trees, and the two candlesticks standing before the God of the earth.
5 And if any man will hurt them, fire proceedeth out of their mouth, and devoureth their enemies: and if any man will hurt them, he must in this manner be killed.
6 These have power to shut heaven, that it rain not in the days of their prophecy: and have power over waters to turn them to blood, and to smite the earth with all plagues, as often as they will.
7 And when they shall have finished their testimony, the beast that ascendeth out of the bottomless pit shall make war against them, and shall overcome them, and kill them.
8 And their dead bodies shall lie in the street of the great city, which spiritually is called Sodom and Egypt, where also our Lord was crucified.
KJV
Where's that beast going to ascend to? Verse 8 right there tells us, it's to Jerusalem where God's two witnesses will be testifying against the beast! Jerusalem is where Lord Jesus was crucified.
Why does God then call Jerusalem that descends from Heaven down to the earth in final the "great city"?
Rev 21:10
10 And he carried me away in the spirit to a great and high mountain, and shewed me that great city, the holy Jerusalem, descending out of heaven from God,
KJV
Just as with everyone Satan does in this world trying to mimic The Father and The Son, the devil is planning to setup the FAKE "great city" in earthly Jerusalem for the end of days just prior to Christ's return. THIS IS WHY Christ points to Jerusalem for the end as the BABYLON HARLOT, because that is where the Antichrist is coming to setup his FAKE kingdom over the entire earth.