(20) And the beast was captured, and with it the false prophet who in its presence had done the signs by which he deceived those who had received the mark of the beast and those who worshiped its image. These two were thrown alive into the lake of fire that burns with sulfur.
This is strikingly similar to something Isaiah said about what would become of the gentile nations after the fall of Jerusalem (the 589 B.C. fall),
On that day the LORD will punish the host of heaven, in heaven, and the kings of the earth, on the earth. (22) They will be gathered together as prisoners in a pit; they will be shut up in a prison, and after many days they will be punished. (Isaiah 24:21-22).
We ought not think of the Roman Empire as one unit throughout history, but many generations who made up the history of Rome. Even the book of Revelation does not consider the beast to be the Roman Empire in its entirety, but only up to the seventh king (Vespasian). Many commentators jump hundreds of years into the future when they get toward the end of the book; but the text does not permit that kind of interpretation. The seven-headed beast is thrown into the pit. This, like Isaiah’s language, is confirmation that God has not forgotten all the terrible wickedness that the gentile nation has done, and that generation will be judged for it (see also 20:11-15). And, like Isaiah specified, “after many days they will be punished,” we must recognize that the throwing into a bottomless pit or a lake of judgment fire does not mean these are immediately being punished for their sins, only that they are held fully accountable, and will certainly be punished for their wickedness. Isaiah describes the pit as a place where a prisoner has been judged and is awaiting their punishment in the future.
One of the things I’ve seen commentators and preachers miss is the fact that the beast of Revelation was currently on its sixth king and the narrative ends with the actions of the eighth, which is not yet the king, but operates under the seventh king (see 17:10, 11). So, when the beast is thrown into the lake of fire, it is still only a seven-headed beast. This is not a problem for those who wish to remain consistent in a book that will “soon take place,” but I find it a terrible problem for those who wish to make the beast the Roman Empire in its entirety. I’m amazed by the position of those who view this text as the fall of the Empire; how was that the “things that must soon take place?” That was to come over four hundred years later (just the Western Empire, the rest of the empire endured much longer). How is four hundred years a short time away? What does that have to do with the seven churches in Asia in the first century? Information about the fall of the empire would be redundant to these brethren. Every nation falls, because they are human nations, if the empire had to fall in the next couple of years from the writing of Revelation, then we may have seen it addressed in the visions of the book, but only if it had any significance to the faithfulness of the churches. This is not a book of fun facts about the future, it was the revelation of Jesus Christ shown to his servants in the first century. The fall of the empire has nothing to do with the book. This scene is showing the Lord’s servants that the wickedness of the Romans who dealing treacherously with the saints will be understood by the Lord and he will hold them accountable, as if in a pit awaiting punishment. The saint need only to endure in faithfulness and the Lord will take care of any concerns.
This text is a summary of the fuller details of the prophecy in Isaiah 66:15-24, particularly verses 15-18,
“For behold, the LORD will come in fire, and his chariots like the whirlwind, to render his anger in fury, and his rebuke with flames of fire. (16) For by fire will the LORD enter into judgment, and by his sword, with all flesh; and those slain by the LORD shall be many. (17) “Those who sanctify and purify themselves to go into the gardens, following one in the midst, eating pig’s flesh and the abomination and mice, shall come to an end together, declares the LORD. (18) “For I know their works and their thoughts, and the time is coming to gather all nations and tongues. And they shall come and shall see my glory”
This is common prophetic language. God often speaks of the judgment of the gentile nations immediately following his judgments against the house of Israel (see comments of 14:9).