The bulk of this material comes from the latter half of The Final End of the Wicked, an article originally published in the Journal of the Evangelical Theological Society in September of 1984 (pages 325-334).
Edward Fudge is a layperson, a lawyer, who has examined the evidence for hell as an eternal conscious torment and found it wanting. In about 1970 he published the book, The Fire That Consumes, a 500 page book that concludes that the case for the traditional understanding of hell is nowhere near as airtight as is normally supposed. Since its publication I have yet to see a convincing rebuttal of his hermeneutical approach to the texts normally supposed to support an ever-tormenting hell fire (whether literal or figurative). What I have seen is a lot of histrionics and proof-texting that ignores the literary and historical context of the scriptures in question.
In the article mentioned first he summarizes some of the most important points he makes in the book about the hermeneutics of the language used to describe final punishment. In particular, seven of the most popular expressions are described in the literary context of their biblical precedents. We will note the most salient points of the article below. The following is abridged for the sake of clarity. For the full impact, refer to the article itself at the link above.
1. “Unquenchable fire. This expression appears in many places (Isa 1:31; 34:10 11; Jer 4:4; 7:20; 17:27; 21:12; Ezek 20:47 48; Amos 5:5 6). Jesus warns of it in Mark 9:43, 48. This is a picture of burning up the trash to destroy it.
2. Undying worms. What of “the worm that does not die” (Mark 9:48)? This comes from Isa 66:24, “And they will go out and look upon the dead bodies of those who rebelled against me; their worm will not die, nor will their fire be quenched, and they will be loathsome to all mankind.” These are dead bodies, not living people or human spirits. This is post-mortem dishonour by refusal to properly bury the bodies.
3. Gnashing of teeth. ‘The phrase “grinding of teeth” appears many times in the OT (see Job 16:9; Ps 35:16; 37:12; Lam 2:16), and it always pictures someone so angry at another that he grinds his teeth in rage, like a mad animal straining at the leash. We see the same usage in the NT, where Stephen’s enemies “gnashed their teeth at him” (Acts 7:54).’
4. Smoke that ascends. This picture comes from Gen 19:24. ‘It is much the same as our image of the mushroom-shaped cloud after an atomic blast. The visible smoke is a certification of accomplished destruction.’ In Isa 34:10 uses the expression to describe complete desolation. ‘The verses following describe a land empty of people, the haunt of desert creatures. Conscious pain has ended there, but “its smoke will rise forever”—the extinction is perpetual.’
5. No rest day or night. In Rev 14:1-5 the third angel cries with a loud voice: “If anyone worships the beast and his image and receives his mark on the forehead or on the hand, he, too, will… be tormented with burning sulfur in the presence of the holy angels and of the Lamb . . . There is no rest day or night for those who worship the beast and his image” (14:9-11). ‘Here the destruction occurs without respite or relief for its victims until it is finished. Their suffering is not exclusively a “daytime” activity, nor it it exclusively a “nighttime” activity.’ [John’s note: Compare Rev. 9:3-18 and 16:8-10 with 14:9-11 for evidence of intense, but limited-duration torments in the same book.]
6. The cup of God’s wrath. ‘This symbol, in the scene at Rev 14:9-11, is a common figure for God’s punishment in both OT and NT (see Job 21:20; Ps 60:3; 75:8; Isa 51:17, 22; Jer 25:27-28; Obad 16; Matt 26:39). The prophets use language like this: “They will drink and drink and be as if they had never been” (Obad 16); they “drink, get drunk and vomit, and fall to rise no more” (Jer 25:27). The figures combine in this passage for the strongest possible picture of punishment. Not all commentators understand this passage to refer to the final end of sinners, of course, and we will not argue that point either way. Whatever the case, the symbols are clear in the light of previous Biblical usage. None of them refers to unending conscious torment in regular usage, and there is no reason to think any refers to it here.’
7. The lake of fire. ‘The lake of fire is the Bible’s last description of final punishment, and it is mentioned four times (Rev 19:20; 20:10,15; 21:8). It is the fiery lake of burning sulfur, the lake of fire and brimstone. The exact expression “lake of fire (and brimstone/burning sulfur)” does not appear anywhere else in Scripture.
‘If one’s prophetic schema sees [the Beast and the False Prophet] as actual persons yet to come, we only note that the text says nothing about human beings “tormented day and night for ever and ever.” This is the single most problematic text in the whole Bible for the extinction of all evil, even though it does not specify human beings. [John’s note: it seems unlikely that the Beast and False Prophet are human beings in light of Rev. 16:13. These seem to be demonic beings who have perhaps possessed human beings.] … As the vision continues, however, “death and Hades” are “thrown into the lake of fire” (v 14). … This is the consummation of God’s victory over his final foe. Death and Hades are certainly abstractions, not persons, and the lake of fire here means their annihilation. Death will be no more—forever.
‘Only now do we find sinners included in this dreadful fate. “If anyone’s name was not found written in the book of life, he was thrown into the lake of fire” (v 15). The “book of life” is a symbol based on the ancient city’s register of living citizens. Whoever is not listed among the living is instead “in the lake of fire.” John makes the identification clear: “The lake of fire is the second death” (v 14). The next chapter repeats the fact with elaboration. Overcomers will inherit the new heavens and new earth, but all classes of sinners “will be in the fiery lake of burning sulfur,” which again, John adds, “is the second death” (21:8). There is no good reason for not taking John’s explanation exactly as it stands, or for importing foreign Platonic definitions of “death” as “separation” into the discussion here. The natural sense is to be preferred, and here it could hardly be made plainer than it is. The final options are “life” or “death.” Everything else we have found throughout Scripture accords with this as well.’
8. Paul’s favorite phrases. ‘Paul’s most common phrases on the subject all picture the total extinction of sinners at the end. … The wicked, he warns, will die (Rom 6:21, 23), perish (2:12), be destroyed (Gal 6:8; 1 Cor 3:17; 2 Thess 1:9; Phil 1:28; 3:19; see also Jude 10). Nor will they ever come back, for this destruction is to be “everlasting” (2 Thess 1:9).
Edward Fudge concludes, “This case rests finally on Scripture. Only Scripture can prove it wrong.”
I strongly recommend reading the entire article linked above and his book. So far, I have seen nothing Scriptural presented against his views that casts any doubt on his major conclusions. What I have mostly seen is quibblings about the meaning of the word “eternal” and the supposed parallel that requires the punishment to equal in duration the reward of the saved. Fudge has an answer that that: death and life are opposites. Eternal death and eternal life strike me as having equal duration, making them parallel enough for me.