Question: "What is the whore of Babylon / mystery Babylon?"
Answer: Revelation 17:1-2 tells us, "Then one of the seven angels who had the seven bowls came and talked with me, saying to me, "Come, I will show you the judgment of the great harlot who sits on many waters, with whom the kings of the earth committed fornication, and the inhabitants of the earth were made drunk with the wine of her fornication."" Revelation 17:5 goes on to say, "And on her forehead a name was written: MYSTERY, BABYLON THE GREAT, THE MOTHER OF HARLOTS AND OF THE ABOMINATIONS OF THE EARTH." Who is this "whore of Babylon" and what is "mystery Babylon"?
Revelation 17:3 gives this description: "Then the angel carried me away in the Spirit into a desert. There I saw a woman sitting on a scarlet beast that was covered with blasphemous names and had seven heads and ten horns." The beast mentioned in this verse is the same beast as in Revelation chapter 13:1, "And I saw a beast coming out of the sea. He had ten horns and seven heads, with ten crowns on his horns, and on each head a blasphemous name." The beast in Revelation chapter 13 is understood to refer to the Antichrist, the man of lawlessness (2 Thessalonians 2:3-4; Daniel 9:27). So, the whore of Babylon, whoever it is, is closely affiliated with the end-times Antichrist.
The fact that the whore of Babylon is referred to as a mystery means that we cannot be completely certain as to her identity. The passage does give us some clues, however. Revelation 17:9 explains, "This calls for a mind with wisdom. The seven heads are seven hills on which the woman sits." Many commentators link this passage with the Roman Catholic Church because in ancient times, the city of Rome was known as "the city on seven hills" because there are seven prominent hills that surround the city. However, verse 10 goes on to explain that the seven hills represent 7 kings or kingdoms, five of which have fallen, one that is and one that is to come. Therefore, the "whore of Babylon" cannot refer exclusively to Rome. Revelation 17:15 tells us, "Then the angel said to me, "The waters you saw, where the prostitute sits, are peoples, multitudes, nations and languages."" The whore of Babylon will have great worldwide influence over people and nations. Verses 10-14 describe a series of eight and then ten kings who affiliate with the beast. The whore of Babylon will at one time have control over these kings (Revelation 17:18), but at some point the kings will turn on her and destroy her (Revelation 17:16).
So, can the mystery of the whore of Babylon be solved? Yes, at least partially. The whore of Babylon is an evil world system, controlled by the Antichrist, during the last days before Jesus' return. The whore of Babylon also has religious connotations " spiritual adultery with the beast being the focus of an ungodly, end-times religious system.