What is Babylon in Revelation?

Already before Revelation, Babylon is mentioned by Peter:

1 Peter 5:13, "The church that is at Babylon, elected together with you, saluteth you; and so doth Marcus my son."

Wikipedia says that Peter therefore must have written from Rome. Let's see what the King James Version (KJV) of the Bible says.

Revelation 14:8, "And there followed another angel, saying, Babylon is fallen, is fallen, that great city, because she made all nations drink of the wine of the wrath of her fornication."

Revelation 16:19, "And the great city was divided into three parts, and the cities of the nations fell: and great Babylon came in remembrance before God, to give unto her the cup of the wine of the fierceness of his wrath."

Revelation 18:2, "And he cried mightily with a strong voice, saying, Babylon the great is fallen, is fallen, and is become the habitation of devils, and the hold of every foul spirit, and a cage of every unclean and hateful bird."

Revelation 18:10, "Standing afar off for the fear of her torment, saying, Alas, alas, that great city Babylon, that mighty city! for in one hour is thy judgment come."

Revelation 18:21, "And a mighty angel took up a stone like a great millstone, and cast it into the sea, saying, Thus with violence shall that great city Babylon be thrown down, and shall be found no more at all."

It seems that Jerusalem having picked up new ideas from Babylon is stated here (Babylon having infiltrated Zion [the original Judaism]):

Zechariah 2:7-12, "Deliver thyself, O Zion, that dwellest with the daughter of Babylon. [...] Sing and rejoice, O daughter of Zion: for, lo, I come, and I will dwell in the midst of thee, saith the Lord. And many nations shall be joined to the Lord in that day, and shall be my people: and I will dwell in the midst of thee, and thou shalt know that the Lord of hosts hath sent me unto thee. And the Lord shall inherit Judah his portion in the holy land, and shall choose Jerusalem again."

Babylon in the end times is compared to the Chaldeans and Sodom and Gomorrah in

Isaiah 13:19-21, "And Babylon, the glory of kingdoms, the beauty of the Chaldees' excellency, shall be as when God overthrew Sodom and Gomorrah. It shall never be inhabited, neither shall it be dwelt in from generation to generation: neither shall the Arabian pitch tent there; neither shall the shepherds make their fold there. But wild beasts of the desert shall lie there; and their houses shall be full of doleful creatures; and owls shall dwell there, and satyrs shall dance there."

Chaldean is interesting here since the Chaldean cipher is often used in the occult, see Table 1, p. 233 and Table 7, p. 235.

"never be inhabited" could be because there will be a New Jerusalem.

Revelation 21:1-2, "And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea. And I John saw the holy city, new Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband."

Revelation 11:8, "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."

Sodom being known for being filled with wicked men and sinners:

Genesis 13:13, "But the men of Sodom were wicked and sinners before the Lord exceedingly."

Isaiah 14:2-4, "And the people shall take them, and bring them to their place: and the house of Israel [spiritual Israel, see Romans 11] shall possess them in the land of the Lord for servants and handmaids: and they shall take them captives, whose captives they were; and they shall rule over their oppressors. And it shall come to pass in the day that the Lord shall give thee rest from thy sorrow, and from thy fear, and from the hard bondage wherein thou wast made to serve, That thou shalt take up this proverb against the king of Babylon, and say, How hath the oppressor ceased! the golden city ceased!"

Babylon also being "the golden city".

Isaiah 1:1, "The vision of Isaiah the son of Amoz, which he saw concerning Judah and Jerusalem in the days of Uzziah, Jotham, Ahaz, and Hezekiah, kings of Judah."

Isaiah 1:1-10-11, "Hear the word of the Lord, ye rulers of Sodom; give ear unto the law of our God, ye people of Gomorrah. To what purpose is the multitude of your sacrifices unto me? saith the Lord: I am full of the burnt offerings of rams, and the fat of fed beasts; and I delight not in the blood of bullocks, or of lambs, or of he goats."

Isaiah 1:21, "How is the faithful city become an harlot! it was full of judgment; righteousness lodged in it; but now murderers."

This last one reminds of

Revelation 17:5, "And upon her forehead was a name written, Mystery, Babylon The Great, The Mother Of Harlots And Abominations Of The Earth."

Revelation 17:18, "And the woman which thou sawest is that great city, which reigneth over the kings of the earth."

Continuing with Isaiah,

Isaiah 2:3-4, "And many people shall go and say, Come ye, and let us go up to the mountain of the Lord, to the house of the God of Jacob; and he will teach us of his ways, and we will walk in his paths: for out of Zion shall go forth the law, and the word of the Lord from Jerusalem. And he shall judge among the nations, and shall rebuke many people: and they shall beat their swords into plowshares, and their spears into pruninghooks: nation shall not lift up sword against nation, neither shall they learn war any more."

Isaiah 3:3, "For, behold, the Lord, the Lord of hosts, doth take away from Jerusalem and from Judah the stay and the staff, the whole stay of bread, and the whole stay of water."

Luke 21:20-24, "And when ye shall see Jerusalem compassed with armies, then know that the desolation thereof is nigh. Then let them which are in Judaea flee to the mountains; and let them which are in the midst of it depart out; and let not them that are in the countries enter thereinto. For these be the days of vengeance, that all things which are written may be fulfilled. But woe unto them that are with child, and to them that give suck, in those days! for there shall be great distress in the land, and wrath upon this people. And they shall fall by the edge of the sword, and shall be led away captive into all nations: and Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled."

Some say this is talking about the destruction of Jerusalem in 70 AD, but before verse 20 to 24, it writes

Luke 21:11, "And great earthquakes shall be in divers places, and famines, and pestilences; and fearful sights and great signs shall there be from heaven."

Revelation 6:12, "And I beheld when he had opened the sixth seal, and, lo, there was a great earthquake; and the sun became black as sackcloth of hair, and the moon became as blood;"

which is likely about the end times, while after verse 24 it writes

Luke 21:31, "So likewise ye, when ye see these things come to pass, know ye that the kingdom of God is nigh at hand."

which is clearly about the end times.

Also Matthew 23:37-38, "O Jerusalem, Jerusalem, thou that killest the prophets, and stonest them which are sent unto thee, how often would I have gathered thy children together, even as a hen gathereth her chickens under her wings, and ye would not! Behold, your house is left unto you desolate. For I say unto you, Ye shall not see me henceforth, till ye shall say, Blessed is he that cometh in the name of the Lord."

which is the end of Matthew 23 and continues in Matthew 24,

Matthew 24:1-3, "And Jesus went out, and departed from the temple: and his disciples came to him for to shew him the buildings of the temple. And Jesus said unto them, See ye not all these things? verily I say unto you, There shall not be left here one stone upon another, that shall not be thrown down. And as he sat upon the mount of Olives, the disciples came unto him privately, saying, Tell us, when shall these things be? and what shall be the sign of thy coming, and of the end of the world?"