Jesus is often credited with speaking the most on hell out of the pool of biblical characters. This is partially true. Besides the direct references to a valley called “Gehenna” (which translators pull out of its context by translating it “hell”), Jesus spoke a lot on the topic of judgment. Jesus’s particular method for communicating this judgment was to borrow the imagery from the OT Scriptures. (This is more pronounced in Matthew due to the intended audience being Jews.) In a previous post, I looked at the principles of judgment in the OT. To summarize, the Psalms anticipate a world where the righteous inherit the earth and the wicked are nowhere to be found. The Prophets anticipate the same. Time and time again, God’s wrath is pictured in the form of a consuming fire, of death, and of total destruction. It is described in terms of an unquenchable fire (Jer. 17:27) that will not go out until it devours and consumes completely and totally. The result is death. There is not one mention of a punishment after death or a future reckoning where the wicked will endure endless torture. The applications of these principles—The Great Flood, The burning of Sodom and Gomorrah—serve as prototypes for the judgment to come.
As I hope to show, the teachings of Jesus are in full agreement with the witness of the OT. I will group these teachings roughly into three categories: those that use imagery involving darkness/teeth, fire, and a miscellaneous category for everything else. As with all methods of grouping, some teachings could easily belong to multiple categories. However, I find these categories to be a helpful way to organize the information.
Darkness, Weeping, Gnashing of Teeth
See: Matt.8:11-12, Matt. 13:48, Matt. 24:50-51, Matt. 25:30, Luke 13:27-29
The darkness, at its bare minimum, can depict being thrown out of a wedding feast and into the outside darkness, far enough so that the lights inside no longer illuminate the area. Beyond this, the prophets use darkness to describe “the day of the Lord”, or a day of judgment (Joel 2:2, Amos 5:18, Nahum 1:8, Zeph. 1:15 among others). It is a symbol and figurative language that accompanies the judgment of God. In the occurrences in Matthew, and in several OT occurrences, darkness is a figurative place. It is there, the darkness, that the wicked will be driven/thrown into. Every instance of people being thrown into the darkness follows an instance where these same people miss an opportunity to belong to the kingdom of God, whether it be that specific phrase or an allusion such as a wedding feast or the joy of the master. The reason these people are thrown into the darkness shapes their reactions, which, in Jewish fashion, are communicated by the imagery of weeping and gnashing of teeth.
The idea that those who are sentenced to punishment weep and gnash their teeth is often used to support the idea that those who are thrown into hell are tormented consciously and eternally. However, there is not a sound precedent for this reading. Weeping, as a Hebrew symbol, implies fear and the grief and misery that accompany great loss. For example, people weep for the death of others (Is. 16:9, Jer. 9:1, 48:32, Rev. 18:9) or when Jerusalem is destroyed (Is. 22:12). James warns the corrupt rich of the coming judgment and that they should weep in fear (James 5:1). Lamentations in its entirety is devoted to weeping. Weeping then, does not imply that these people are experiencing torment so much as the pain of emotional loss. We might be able to stretch this further by saying that weeping could signify an extreme dread of a punishment to come, but anything beyond this would be reading too much into the text.
Grinding of teeth is used as a symbol for bitterness, fury, and anger. In most cases, this action describes the anger of someone who is about to kill another (Job 16:9, Ps. 35:16, 37:12, Lam. 2:16, Acts 7:54). Psalm 112 is an example of a reverse situation, and I think Jesus has this psalm in mind when he uses the imagery. The psalm ends with this: “the wicked man sees it and is angry; he gnashes his teeth and melts away; the desire of the wicked will perish!” Even as the wicked person directs his anger towards the righteous, he finds himself powerless as to his fate and melts away into nothing.
With all of this in mind, the teachings of Jesus using the imagery of darkness, weeping, and gnashing of teeth describe the reactions and emotions of those punished to their sentence—banishment from the kingdom of God. These reactions do not appear to signify actual pain from the mechanism of punishment but simply a response to the sentence. What they certainly do not teach is the eternal torment of those punished. That conclusion requires an awful lot of reading into the text things that are not there.
See: Matt. 3:10-12, 7:19, 13:30, 13:36-43, 25:41-46, John 15:6
The fire Jesus speaks of is one that ultimately brings an end to whatever and whoever experiences it. Every tree that does not bear good fruit will be thrown into the fire (Matt. 3:10, 7:19). The wicked will be like chaff, weeds, and branches thrown into the fire (Matt. 3:12, 13:30, 13:36-43, John 15:6). Matt 3:12 speaks of an “unquenchable fire”. Rather than being a fire that eternally torments, this unquenchable fire continues to burn until nothing is left, as numerous OT references acknowledge (Is. 1:31, 34:10-11, Jer. 4:4, 7:20, 17:27, 21:12, Ezekiel 20:47-48, Amos 5:6).
Weeping and gnashing of teeth will occur in “the fiery furnace” just as in the “outer darkness”, which is enough to tell us that these figures should be read in a metaphorical light. The “fiery furnace” of Matt 13:36-43, 48-50 alludes to the story of Shadrach, Meshach, and Abednego being tossed into a fiery furnace for their refusal to worship a golden idol. The crucial difference between the two situations is telling. Unlike these righteous three, the wicked will have no God to save them from the all-devouring flames. They will waste away, like weeds thrown into an open flame, into nothing.
One may reasonably raise the objection of Matt. 25:41-46. The phrases “eternal fire” and “eternal punishment” are concepts that I grew up with and considered synonymous with an eternal hell of torment. For reference, here is the section in its entirety:
41 “Then he will say to those on his left, ‘Depart from me, you cursed, into the eternal fire prepared for the devil and his angels. 42 For I was hungry and you gave me no food, I was thirsty and you gave me no drink, 43 I was a stranger and you did not welcome me, naked and you did not clothe me, sick and in prison and you did not visit me.’ 44 Then they also will answer, saying, ‘Lord, when did we see you hungry or thirsty or a stranger or naked or sick or in prison, and did not minister to you?’ 45 Then he will answer them, saying, ‘Truly, I say to you, as you did not do it to one of the least of these, you did not do it to me.’ 46 And these will go away into eternal punishment, but the righteous into eternal life.”
In a previous post, I dealt with the question of eternal (aiónios) and what the word means and how it should be applied to Matt. 25:46. Eternal, when modifying a verb of action, often refers to the endless result of a process or act, not the duration of the process or act itself. Eternal can also describe a quality of a thing. In the case of “eternal life”, eternal refers more to the quality of life a believer already possesses than the duration of believer’s future life, though both aspects cannot be ignored. In this specific case, eternal could refer to the fire as having its origin with the Eternal One. Though I have not found a commentator that has expressed this idea yet, I think it could also be an eternal fire in the sense that it is metaphor for the holiness of God. After all, God’s holiness judges what is evil and purifies what is unclean, and God Himself is eternal. These are only possibilities however. What is certain is that eternal possesses a quantitative (timely) aspect to it. The result of the act of fire/judgment lasts for eternity, and this result is utter extinction. This is how Jude understood it, as he wrote that Sodom and Gomorrah “serve as an example by undergoing a punishment of eternal fire.” (Jude 7) These cities no longer burn today. They have ceased to be.
We should also be careful to not gather too much from the parallel present in verse 46. As I have reasoned previously, “eternal punishment” does not have to mean a punishment that lasts forever in duration. In a far greater number of places, the biblical authors appear to imply that the wicked will meet a definite end. Though directed towards Matt. 10:39 and not 25:46, I think this quote by Fudge is equally applicable here:
“First, since “life” may mean more than mere existence but never (to our knowledge) means less, on what basis can “loss of life” mean less than the loss of existence, even though here it obviously implies the loss of far more? Eternal “death” involves more than temporal “death”, but surely it involves no less.”
See: Matt. 5:25-26, 7:13-14, 10:39, 18:34-35, Luke 12:58-59, 19:14-27, John 3:16
There are several other teachings that do not fall under the previous categories that should be considered. According to Matt. 7:13-14, the gate that leads to destruction is wide, whereas the gate that leads to life is narrow and hard to find. This has in mind the kingdom of God as a city. An ancient city, such as Jerusalem, would have been surrounded by a wall with gates for entering and exiting. These gates would be closed at night and in times of danger, save for the narrow gate, a small gate that would only allow for one person to enter at a time, and only if this person’s name was written on the city’s role of inhabitants. Jesus uses this image to emphasize the need to escape the coming destruction and enter into the kingdom of God. The way is hard, but the choice is between hardship now and life later or easiness now and doom later 
Another image Jesus uses to teach on the final judgment is that of a jailer (Matt. 5:25-26, 18:34-35, Luke 12:58-59). The one jailed will not be freed from prison until he has paid the last penny of his debt/fee. We need to be careful not to make too much of this unclear statement. I would argue that Jesus places the emphasis on the finality of the prison sentence. The man thrown in prison is helpless and hopeless to pay off his debt. If we were to make a real life example of this, the person thrown in prison would never leave and eventually die. Considering the other images Jesus used concerning punishment, I think this view fits with the rest of Scripture.
Last, but certainly not least, the biblical authors have Jesus say that the punishment for disobedience is death (Matt. 10:39, Luke 19:14-27, John 3:16). I find it extremely ironic that the most-quoted verse in the entire Bible sets “perish” as the eventual penalty for sin. The one who believes will inherit eternal life. The one who sins will perish.
Jesus continues where the OT leaves off. His words are not full of the sort of language one finds in the intertestamental language, as, by comparison, Jesus is quite conservative when it comes to speaking on judgment. He applies the images and allusions in a way that reflects the words of the prophets and psalmists before him. Whether Jesus in the synoptic gospels directs his warnings to Israel because of the future destruction of Israel/Jerusalem or because of the final judgment, I am undecided. I admit I hold an admiration for the partial-preterist (many prophecies/promises past-fulfilled in the destruction of the temple in 70AD) theologians out there. Regardless of their application, the teachings of Jesus are principles and thus can be applied beyond their specific applications and contexts. This is not a complete list however. Jesus makes frequent use of another Jewish symbol of judgment—Gehenna—which, along with the undying worms of Isaiah 66:24, deserves its own separate post.
 Edward William Fudge, The Fire That Consumes. 2e, pg. 179
 Fudge, pg. 166-167