14 ¶ These shall make war with the Lamb, and the Lamb shall overcome them: for he is Lord of lords, and King of kings: and they that are with him are called, and chosen, and faithful. 15 And he saith unto me, The waters which thou sawest, where the whore sitteth, are peoples, and multitudes, and nations, and tongues. 16 And the ten horns which thou sawest upon the beast, these shall hate the whore, and shall make her desolate and naked, and shall eat her flesh, and burn her with fire. 17 For God hath put in their hearts to fulfil his will, and to agree, and give their kingdom unto the beast, until the words of God shall be fulfilled. 18 And the woman which thou sawest is that great city, which reigneth over the kings of the earth.
2Thessalonians 2:8 And then shall that Wicked be revealed, whom the Lord shall consume with the spirit of his mouth, and shall destroy with the brightness of his coming
These ten kings and the beast make war with Christ and His people who are called, chosen, and faithful. The verses are numerous but to be singled out by Christ for service, to be chosen by virtue of your willingness to answer that calling, and to stay true to the faith that He is God walking as God in the flesh on earth, and that salvation comes only through Him, is the essence of salvation and eternal life. They are predestinated by virtue of their belief and obedience to be like Him; called by the Holy Ghost, justified by faith, and glorified at the resurrection. One example is Romans 8:28-30.
These are those who have overcome, who believed on Christ until the end, even their own deaths, which you can see if you have been reading from the beginning.
They that are with him is another evidence that His people have been removed to Heaven to come back with Christ. This conquest of the ten kings and the beast comes after Mystery Babylon is destroyed by them.
Here is a classic metaphor for waters being a type of peoples. We can now go back and perhaps see the word sea as a mass of humanity and pay particular attention to earth as a metaphor in the following verses.
Revelation 13:1 And I stood upon the sand of the sea, and saw a beast rise up out of the sea, having seven heads and ten horns, and upon his horns ten crowns, and upon his heads the name of blasphemy.
Revelation 13:11 And I beheld another beast coming up out of the earth; and he had two horns like a lamb, and he spake as a dragon.
Mystery Babylon rules over the earth as its administrative and religious center and the beast and his ten kings turn on it to destroy it. The next chapter deals with why God has ordained its destruction. Mystery Babylon is supported by the beast until he decides to turn on it to consolidate his power to make himself supreme. Totalitarian power does not like to share what it has gained.