19:20And the beast was seized, and with him the false prophet who performed the signs in his presence, by which he deceived those who had received the mark of the beast and those who worshiped his image; these two were thrown alive into the lake of fire which burns with brimstone.

And

  1. THE BEAST was SEIZED, and with him
  2. the FALSE PROPHET who performed the SIGNS in his presence,

These are two of the members of the "UNHOLY TRINITY": Satan, the BEAST (Revelation 13:1-10) playing the counter part to Christ, and the FALSE PROPHET (Revelation 13:11-18) playing a bad imitation of the Holy Spirit. They were the henchmen/leadership who performed SIGNS to deceive the non-believers in Christ. Suddenly, on the verge of the final battle, they simply were SEIZED. By whom it isn't stated, but one may imagine that it is the One who is redeeming the earth (Revelation 5:5,7). He is leading the heavenly ARMY (verse 11 and 14). When the leadership in the form of two of the UNHOLY TRINITY is gone, the hopes of "the rest" (next verse) are dashed......they realize they had made the ultimate mistaken choice.

by which he DECEIVED

  1. those who had RECEIVED the MARK OF THE BEAST and
  2. those who WORSHIPED his image;

Notice how counterfeit these two deceptions are:

  1. Christ's gift of salvation is free. Contrast that with those who received the MARK of the BEAST. They took the MARK in order to eat and to do business (Revelation 13:17).
  2. The act of worship is a (holy) spirit thing. God is a SPIRIT, and we must WORSHIP Him in Spirit and Truth (John 4:7-24-38). Contrast that with those who WORSHIP the beast's image in direct violation of God's commandment (Deuteronomy 5:6-9-21).

these two were thrown ALIVE into the LAKE OF FIRE which burns with brimstone.

This is the first mention of the LAKE OF FIRE (the other references are Revelation 20:10, Revelation 20:14, Revelation 20:15, and Revelation 21:8). The order in which the LAKE OF FIRE is filled appears to be, the BEAST and FALSE PROPHET, Satan (1000 years later), and the rest, "anyone's name was not found written in the book of life" (Revelation 20:14-15). The LAKE OF FIRE contains EVIL for eternity. EVIL itself apparently doesn't ever die. Just as believers in Christ have everlasting/eternal life, so to those who chose EVIL have an everlasting existence (that may be an understatement!). Since EVIL exists forever, this may be one explanation why the New Jerusalem has gates and has angels guarding the gates (Revelation 21:9-12-14).

This is the fulfillment of Daniel's vision, Daniel 7:9-11-12, albeit Daniel sees their bodies destroyed (but not the EVIL?). Isaiah 66:22-24 talks about the same thing. The BEAST and the FALSE PROPHET remain ALIVE in the LAKE OF FIRE because they are not consumed or annihilated. They are still there 1000 years later (Revelation 20:10). At that time, they have been and will be tormented day and night forever.........and there is no reason to torment something that is dead or totally consumed.