Can demons die? The evidence of Scripture does not disallow it. Indeed, Ezekiel 28:11-19—a well-known passage describing Satan's origins, character, rebellion, and fate—prophesies in verses 18-19:
Therefore [because of your iniquities] I brought fire from your midst; it devoured you, and I turned you to ashes upon the earth in the sight of all who saw you. All who knew you among the peoples are astonished at you; you have become a horror, and shall be no more forever. (Emphasis ours.)
Many people believe this applies to a physical “king of Tyre” referenced in verse 11, but the context describing the one who became Satan—“the anointed cherub who covers” (verse 14), who was “the seal of perfection” (verse 12) and “in Eden, the garden of God” (verse 13)—continues without interruption through verse 19. Taken at face value, this passage tells us that God, who created the angels who chose to sin, can extinguish their lives through an annihilating fire. Trying to explain verses 18-19 as a metaphor for Satan and his demons being imprisoned in darkness forever makes a mockery of their plain sense. In fact, the words of Ezekiel 28 sound amazingly like death in the Lake of Fire.
Thus, if those suffering torment in Revelation 20:10 are Satan and the demons, they, too, will experience the torture and excruciating pain of the fervent heat of the Lake of Fire. Perhaps with them, being composed of spirit, it will last for a longer, though still indeterminate, time before they expire. The Bible's use of aiôn makes the length of their torment vague. Perhaps they will suffer some form of torment while imprisoned in the abyss (see Isaiah 24:21-23). In any case, we can understand their torment “day and night forever and ever” to indicate unstinting thoroughness—that God will not shirk in giving them the most painful and complete punishment, as they rightfully deserve.
Our Savior is the great Judge of all (II Timothy 4:1). His judgments are flawless; He demonstrates perfect justice and mercy at all times. Though the punishments that the wicked and the demons will receive may seem ghastly, they fit their crimes. There is no unrighteousness with God (Romans 9:14).
As Christ's disciples, resurrected to eternal life in God's Kingdom, we will be able to look forward to an eternity of peace and security, of never-ending joy and growth, because He will have removed all evil from the universe. Peter tells us that once God purifies all things, only righteousness will dwell in the new heavens and new earth (II Peter 3:13). There will be no taint of sin anywhere in creation, which can be true only if God has completely erased the existence of all sin and all sinners, including the Adversary and his demons.
As Peter writes in the same passage, we must soberly consider God's perfect judgment for sin and His wrath against it. We are living through our time of judgment right now, and falling away and falling under God's wrath are still possibilities if we fail “to make [our] call and election sure” (II Peter 1:10). Knowing God's perfect judgment should spur us to live holy and godly lives, “hastening the coming of the day of God” (II Peter 3:11-12, 14).