continued from yesterday
It is well above my--or your--pay grade to determine what God does with hell. What we might do is clarify a little what the Bible seems to say and what it doesn't likely say about it. First, as far as the Bible is concerned, hell is a distinctly New Testament idea. The vast majority of the Old Testament is either silent about the afterlife or explicitly denies any meaningful existence after death.
Job 7:9-10 captures the Old Testament understanding well: "one who goes down to the grave does not return. He will never come to his house again; his place will know him no more." I used to think that Job's wife was horrible when she was urging Job to curse God and die. To me, she was wishing him to go into hell forever. But she actually was urging him to put himself out of his misery. In her way of thinking, after he cursed God, God would kill him and then he would no longer be in pain.
"Sheol" in the Old Testament is thus not a place of eternal torment. It is merely the place where all the dead go when they die. It is a place of generally mindless, shadowy existence. Psalm 6 prays, "save me because of your unfailing love. Among the dead no one proclaims your name. Who praises you from the grave?"(Ps. 6:4-5). Ecclesiastes of course puts it in its starkest terms, "The dead know nothing... never again will they have a part in anything that happens under the sun" (Eccl. 9:5-6).
Death in the Old Testament can thus be a punishment for sins in life, but it was not understood at that time as a gateway to eternal punishment. When Achan and his family are stoned in Joshua, that is the end of the matter as far as Joshua is concerned. The Israelites did not think they were sending Achan's family to hell. Their death took care of the sin.
The only real exception is Daniel 12:2-3, the only passage in the Old Testament that everyone agrees clearly teaches resurrection.  In Daniel, some (not all) are resurrected for reward and some (not all) are resurrected for "everlasting contempt." Daniel does not tell us what everlasting contempt is. I hold many individuals from the past in everlasting contempt as a category of shame.
As with so many key Christian concepts, the crucial background to the New Testament came in the two to three hundred years immediately preceding Christ. It is during this time that an understanding of hell developed in Jewish apocalyptic literature (1 Enoch, the Dead Sea Scrolls). And it is this literature rather than the Old Testament that is the primary background for the kind of imagery of Gehenna that we find in the New Testament.
We have already seen some of the imagery of hell in the gospels. The gospels clearly teach that there will be a judgment of the wicked dead at the judgment. However, given some of the questions people are asking about hell right now, it might be useful to revisit them with the question of "how long" they say hell will last. And here we only find the one statement in Matthew 25:46 about eternal punishment.
What is eternal punishment? We probably rightly take it to mean a punishment that goes on in real time forever. Others might try to interpret it differently. For example, annihilation is a final punishment that continues forever. It is a kind of eternal punishment. I doubt that is what Matthew 25 means, but I can see someone trying to interpret the statement in that way.
The other passages are more ambiguous when it comes to duration. The other references to Gehenna in Matthew and Luke talk about being thrown into hell but don't mention how long the torment lasts. Mark 9:43 and 45 speak of the fire of Gehenna never being quenched. Does this mean that the torment of an individual never ends? It probably does.
The word "Hades," on the other hand, is the Greek equivalent of Sheol and refers to the place of the dead in general without specific reference to reward or punishment. The fact that Capernaum will be brought down to Hades could only mean that it will be destroyed in the judgment (Matt. 11:23). However, despite the generality of the word, the overall context of Matthew probably implies everlasting punishment.
Paul never mentions hell in any of his writings. Revelation of course speaks of the lake of fire, into which the beast and those who worshiped him are thrown alive (19:20). Similarly, all the dead rise and are judged, with the wicked thrown into the lake of fire, along with death itself. It is specifically stated that Satan and the beasts of Revelation are then tormented day and night forever (Rev. 20:10). The best assumption is that this is also true of the other wicked, although Revelation does not explicitly say so.
Therefore, after looking at the Bible on hell, we find at least two instances where the punishment seems to be never-ending (Matt. 25:46; Rev. 20:10). Over the centuries, this understanding of hell has crystallized and solidified in Christian teaching. Indeed, the place hell holds in our thinking may come as much from medieval Christianity as from the role it plays in the Bible itself. In the end, you and I cannot decide what hell is, so our best bet is to avoid it at all costs and to share the good news of Christ to as many others as possible in hope that they will avoid it as well.
 Other passages are debated, of course, like Isaiah 26 and Ezekiel 37.