John Calvin asserts that the plain meaning of the text is, that the wicked shall have a bad conscience as an executions to torment them without end… and finally, that they shall tremble and be agitated in a dreadful and shocking manner as if a worm were gnawing the heart of a man, or a fire were consciousness it and yet thus conscience he did not die (John Calvin, Commentary on the book of the prophet Isaiah, vol. 4 rep. grand rapid: win B. E. Edvans Pub. Co., 1948). 4:438

According to Archer and Waltke, Theological Wordbook of the Old Testament (vol. 2, Moody Press, 1580) pp. 571-972, the worm in Isaiah 66:24 means “worm maggot or larvae… of certain kinds of insects, primarily flies, moths and beetles which devour decaying matter including corpses”. A worm especially one which springs from putrefaction Ex. 16:20; Isa.14:11; 66:24

In other words neither Isaiah nor Christ was talking about immortal worms. The vermin of which they spoke – maggots – do not die because they turn into flies. The flies then lay eggs that hatch into more maggots (the larvae of flies perpetuating the cycle. It is a wounds which occur in decaying organic matter or in soros [ex. 16:20; Isa. 14:L; 66:24) TISBE, vol. 14, Hendrickson Pub. James Or. Ed, 1939] p. 310

This helps us better understand Christ’s words. In that time, when the bodies of dead animals or executed criminals were cast into the burning trash heap of Gehenna, those bodies would be destroyed by maggots, by the fires that were kept constantly burning there, or a combination of both. The worms are mentioned in connection with the dead bodies because they hasten the decomposition and represent the ignominy of corpses deprived of burial (Jer. 25:33; Isa 14:11, Job 7:5; 17:14; AcB 12:23

Observe the presence of the word “carcasses” (Hebrew, pegerim) in that passage and think for a moment of what it means. What is “carcasses”? That is simply, a “lifeless corpse” or “dead body” of human being. The same book describes what is meant by “carcass” of men. “Thou art cast out of thy grave…as a carcass trodden under feet” (Isa. 14:19). “Behold they were all dead corpse” (Isa. 37:36).

A “lifeless corpse or dead body” cannot be suffer a conscious torment in anyway; because to torment is for the ‘living while ‘destruction and decay is for the dead. In other words, the fire and worms in Isaiah destroy dead corpses; they do not torment living human beings. And those are said to be the same fate happen to Gehenna. It is the picture of corpses thrown into a garbage dump of the universe where they are destroyed by a process that will not stop until it has completely purified God’s creation from both sin and sinners (Isa. 66:22-24).

Any interpretation of Mark 9:48 should not contradict the passage in Isaiah that gives it its true setting. The final verse of Isa. 66:22-24, says that the fire and worms destroy dead corpses. They do not torment live human beings. Neither the fires nor the worms of Gehenna preserve anything; both are agents of destruction. We read in verse 24 that “”people will go out and look upon the dead bodies of those who rebelled against me, their worm will not die, nor will then fire be quenched and they will be loathsome to all mankind.”