Spirits can die
At the present time only God the Father and Jesus Christ possess immortal life. It is not true, however, that all spirit-beings are immortal simply because they are composed of spirit. Jesus reveals not only the punishment of those who refuse to live righteously but also what will ultimately happen to Satan and other evil spirits:
"Then shall He also say to those on the left, 'Depart from Me, you cursed ones, into the eternal fire, which has been prepared for the devil and his angels.'" (Matthew 25:41)
Why is a fire prepared for Satan and his demons if they cannot be harmed by it? Many make the assumption, based on a misinterpretation of what Jesus taught in Luke 20, that angelic beings inherently have immortal life and CANNOT be put to death.
"And Jesus answered and said to them, 'The children of this age marry and are given in marriage; But those who are accounted worthy to obtain that age, and the resurrection from the dead, neither marry nor are given in marriage; And neither can they die any more, for they are equal to the angels, and are the children of God, being children of the resurrection.'" (Luke 20:34-36)
In these few verses Jesus is only answering the Sadducees' question of marital status in the Kingdom of God. He is NOT addressing the question of eternal life or immortality. His primary point is that like angels who do not procreate, humans who are resurrected and changed into spirit will also not produce children. Those who are part of the first resurrection, which occurs when Jesus returns, are given immortal life as sons of God. They will have life inherently within themselves and never be able to die (see 1Timothy 1:17, 6:12-16, Hebrews 2:9:10, etc.).
Angels are eternal, not immortal, spirit beings. Their life, as shown in many scriptures, can be terminated by the One who gave it to them.
What do angels FEAR?
What is it that evil spirits know about God that would make them tremble in fear? This question is answered in Mark's account of Jesus meeting a man in a synagogue who was possessed with a demon.
"Now a man who had an unclean spirit was in the synagogue; and he cried out with a loud voice, saying, 'Ah! What have we to do with You, Jesus the Nazarean? HAVE YOU COME TO DESTROY US? I know Who You are, the Holy One of God.' And Jesus rebuked him, saying, 'Be silent, and come out of him.'" (Luke 4:33-35)
In verse 34 above the word destroy is a translation of the Greek word appolumi. This word, which is Strong's Concordance #G622, means to destroy fully and completely. This same word is also used to describe the utter destruction of people and places (Matthew 10:28, Luke 17:29, etc.). The question asked by the demon is instructive as it tells us something about their life and existence.
The Ultimate Punishment
At the end of the millennial rule of Jesus on earth Satan will be allowed one last great deception. He will then receive his ultimate and final punishment from God for his rebellion and sin.
"Now when the thousand years have been completed, Satan shall be loosed out of his prison; And he shall go out to deceive the nations that are in the four corners of the earth, Gog and Magog, of whom the number is as the sand of the sea, to gather them together for war. Then I saw them go up upon the breadth of the earth and encircle the camp of the saints, and the beloved city; and fire came down from God out of heaven and consumed them; And the Devil, who deceived them, was cast into the lake of fire and brimstone, where the beast and the false prophet had been cast; and they, Satan and the demons, shall be tormented day and night into the ages of eternity." (Revelation 20:7-10)
Satan will not endure everlasting punishing. He will, instead, have his existence terminated. He will cease to exist with no hope of ever being brought back to life. The "ages" spoken of in verse 10 is the time when the existence of physical humans on earth will end. It is a time when a new age will begin and the mystery of why God made man is revealed.
Although Ezekiel chapter 28 seems to be a prophecy about the human king of Tyre, the description of his appearance and responsibilities CLEARLY point to it referring to Satan.
"'Son of man, lift up a lamentation over the king of Tyre, and say to him, 'Thus says the Lord GOD, 'You seal up the measure of perfection, full of wisdom and perfect in beauty. You have been in Eden the garden of God; every precious stone was your covering, the ruby, the topaz, and the diamond, the beryl, the onyx, and the jasper, the sapphire, the turquoise, and the emerald, and gold. The workmanship of your settings and of your sockets was prepared in you in the day that you were created. You were the anointed cherub that covers, and I set you so; you were upon the holy mountain of God; you have walked up and down in the midst of the stones of fire.'''
"'You were perfect in your ways from the day that you were created, until iniquity was found in you. By the multitude of your merchandise they have filled your midst with violence, and you have sinned. Therefore I will cast you as profane from the mountain of God, AND I WILL DESTROY YOU, O covering cherub, from among the stones of fire.''' (Ezekiel 28:14-16).
In Ezekiel 28, the Hebrew word from which we get the English word "destroy" CANNOT mean anything other than total destruction.
"'Your heart was lifted up because of your beauty; you have corrupted your wisdom by reason of your brightness. I will cast you to the ground; I will lay you before kings, that they may behold you. By the multitude of your iniquities, by the unrighteousness of your trade, you have profaned your sanctuaries; therefore I brought forth a fire from your midst; it shall devour you, and I will bring you to ashes upon the earth, before the eyes of all who see you. All who know you among the people shall be astonished at you; you became a terror, and you will not be any more.'" (Ezekiel 28:17-19).
The fire that will come from within the devil will consume him. He will be put to a final death and turned into ashes. The ultimate penalty for committing willful sin is eternal death (Romans 6:23). The Lake of Fire in which evil spirits and humans will be cast is a physical place that burns with real fire. Because both evil spirits and people will be tossed into the same physical fire (Revelation 20:7-10) and become ashes that will be trodden under the feet of the righteous (Malachi 4:1-3), it seems likely that God will change both evil spirits and people into flesh before their destruction.
The worst fate
Is there a fate, for some spirits, worse than being dead forever? Notice what some evil spirits asked Jesus:
"And when He had come to the other side into the country of the Gergesenes, there met Him two who were possessed by demons coming out of the tombs, so violent that no one was able to pass by that way. And they cried out at once, saying, 'What do You have to do with us, Jesus, the Son of God? Have You come here to TORMENT US before the time?' Now there was far off from them a herd of many swine feeding; And the demons pleaded with Him, saying, 'If You cast us out, allow us to go into the herd of swine.'" (Matthew 8:28-31)
Notice that these demons greatly feared that a torment or torture would come to them before the appointed time. What are these demented spirits talking about? Although Jude's letter is mainly a warning to the church about false brethren, it includes information regarding two types of punishment for evil spirits.
"But I myself want to remind you, though you once understood this, that the Lord, after saving a people out of the land of Egypt, the second time destroyed those who did not believe. And the angels who did not keep their own original domain, but deserted their habitation, He is holding in eternal bonds under darkness unto the judgment of the great day. Just as Sodom and Gomorrah - and the cities surrounding them, in the same manner as them - having given themselves over to sexual debaucheries, and having gone after different flesh, are themselves exhibited as a perpetual example of undergoing the punishment of eternal fire" (Jude 5-7).
These verses show that some rebellious angels are chained in a prison until the day they will be punished by fire. However, in verse 13, Jude makes a statement about what will be the punishment of a second group of rebellious angels.
"Raging waves of the sea, casting up like foam their own ignominious shame; wandering stars, for whom has been reserved the blackest darkness forever!" (verse 13).
From this scripture it seems likely some evil angels will remain in a prison of blackness and darkness forever. God does not need to "do" anything special with such rebellious spirits. He will likely just leave them in another dimension where there is no escape. The destiny of these demons is to have their own twisted, perverted minds torment them. They will forever reside in the darkness of existence they created for themselves. They will be their own tormentors, their own worse enemy, forever.