In a brief post several months ago I weighed into the debate over hell and the doctrine of eternal conscious torment by proposing some alternative ways of approaching the subject. Part of the reason this debate tends to get so easily convoluted is that there are several different words in Scripture which have regularly been translated into the one English word "hell"--and then there are several other phrases and concepts which are routinely assimilated into that traditional portrait. This has resulted in a great deal of confusion, as we are automatically inclined to misunderstand what those words and phrases would have meant in their original historical contexts. In order to understand what the Bible has to say on the subject, we must cut through all of the anachronistic baggage which has crept up around the biblical phrases like moss on an old building; we must approach the text on its own terms, as it would have been heard in the time and place in which it was written. To this end, my good friend Mark Edward (who has a fantastic biblical studies blog) has written a very helpful list for nine of the different words and phrases which regularly come up in our thoughts and discussions about hell, shedding much light on the particular connotation which they would have carried in their own historical contexts. I appreciated the insight and clarity of this list so much I had to share it here:
Hell comes from an old, old, old Proto-Germanic word meaning 'to cover up'. The English concept of 'hell' specifically came from the Norse hel, the name of the underworld in Norse mythology, as well as the name of its ruler. The Norse concept of hel has very little resemblance to the contemporary concept of a burning place of torment. The word 'hell' was used as a catch-all rendering for sheol, hades, gehenna, and tartarus when the Bible began receiving English translations. This word really should be left out of the discussion when studying the topic of afterlife punishment, because it's far too ambiguous and inaccurate to be of any help. Sheol is a common Hebrew word used to refer to what we would otherwise call 'the grave', and is treated as contextually synonymous with death, destruction, the earth (as being buried), the sea (as being a deep, dark place), or the pit. In the Hebrew Scriptures, sheol is the fate of all men: to die. The rare occasions that sheol is described beyond the concept of simply being the end of man, it is dark, gloomy, and defined by its 'residents' inactivity, lack of knowledge, memory, thoughts, or even awareness.
Hades originally referred to both the Greco-Roman underworld, as well as the Greek god that ruled over it. Hades was a world of dark, gloomy, nothingness (which is why it was chosen to be the most appropriate Greek word for sheol, when the Jews translated the Hebrew Scriptures into Greek the second or third century BC), but it came to be seen as having different regions within it for either the righteous or unrighteous. When we get to the New Testament, hades is regularly used when citing Old Testament passages that refer to sheol. Very rarely, hades is sometimes used as an illustration for afterlife punishment, but it otherwise continues to carry the simple idea of 'the grave', the state of being dead. In this way, sheol / hades is seen as being the ultimate enemy of Christ, and was conquered through his resurrection. In the Revelation, 'death and hades' are thrown into the lake of fire.
Abraham's Side, (let's face it: the word 'bosom' is weird in contemporary English; the most appropriate modern word is 'chest' or 'side'), is a figure of speech referring to the place of rest for those considered members of the Covenant family (i.e. children of Abraham). Analogy can be drawn to the early custom in the ancient near east that resting against the side of one's master was a sign of honor and favor. So, to be resting at Abraham's side meant one was favored and honored by Abraham (or rather, by the God of Abraham). The phrase originated in reference to the 'side of Abraham, Isaac, and Jacob'. In wider Jewish culture (outside of Jesus' use of the phrase), this place was seen as a part within hades, where the righteous would go apart from the unrighteous. The mere fact that Jesus names Abraham and has him speak in no way means the parable is meant to reflect a literal account. Jesus adapted a common cultural image for the sake of his parable. He even utilizes Abraham's servant from Damascus, Eliezer (in Greek: Lazarus), to illustrate that those who originally were not included in the inheritance of the Covenant people have now been included (Eliezer was set to be Abraham's heir until Isaac was born).
Death is occasionally personified to represent the ultimate enemy of God and his people. Adam's disobedience to God brought death upon all humanity. Through his resurrection, Jesus overturned death. Death, along with hades, will be cast into the lake of fire.
The lake of fire comes from Revelation, where John's vision borrows, but somewhat changes, the river of fire from Daniel 7. In Daniel's vision, the river of fire poured out from God's throne, and was a symbol for his divine judgment against Antiochus IV Epiphanes' for his persecution of the saints of Israel. In John's vision, the lake of fire is the place of divine judgment against the Roman Empire and its Emperors (the beast), and the Caesar cult (the false prophet). Later on, the satan (the dragon), death, the grave, and all of the wicked are likewise cast into the lake of fire. John explains to his readers very explicitly: the lake of fire is a symbol for the second death. The 'first' death (above) was the personified enemy of God and his people, because through sin this 'first' death brought death to even the righteous, including Jesus. The lake of fire, that is, the second death, represents the final punishment that Christ brings at his coming. It is not a depiction of eternal conscious torment. The Roman Empire and the Caesar cult, a kingdom and a religion, do not suffer pain for eternity, they are simply destroyed in their entirety. Death and the grave are concepts, not persons that feel torment; they simply cease to exist.
Bottomless pit is a symbol drawing from two sources.
The first source is the Old Testament concept of 'the sea'. In the Hebrew Scriptures, 'the sea' is used poetically as a synonym for 'the deep' or 'the pit'. In the Hebrew Scriptures, 'the sea' could represent chaos and disorder. In the Hebrew Scriptures, 'the sea', as a symbol for chaos, is sometimes personified as a serpent / dragon / leviathan, sometimes named Rahab, which was an alternate name for Egypt. In poetic metaphor, Egypt is depicted as the ancient enemy of God's people, so God slays Egypt, the dragon called Rahab, splitting apart the sea for the freedom of his people. With the defeat of Egypt / Rahab / leviathan / serpent / dragon / sea / deep / pit, God brings a new life to his Covenant people. The exodus event is described in the Prophets as if it was a new creation event.
This is not coincidental, because several Hebrew poetic passages look back to the time of creation (Genesis One) as the time when God conquered the deep / sea / chaos / dragon. Altogether, this 'God conquers the dragon' metaphor is tied together in Revelation 20 in two ways. First, the dragon is imprisoned in the bottomless pit for a thousand years; the serpent is cast back into the deep; leviathan is imprisoned in his sea. Second, the dragon is permanently destroyed in the lake of fire. With God's conquest of the satan / dragon / bottomless pit / chaos / deep / sea (through Jesus!), God begins a new creation with his Covenant people. (This is why John notices a lack of 'the sea' in his vision; he is saying that there will be no more chaos or sin.)
The second source is that John appears to be borrowing from the Greco-Roman concept of tartarus. In ancient Greco-Roman mythology, tartarus was the place where the old gods (the Titans) were imprisoned by the new gods (the Olympians). In later (but still pre-Christian) Greco-Roman mythology, when hades began to be seen as having different regions for the righteous and unrighteous, tartarus was the place of punishment for the unrighteous. They would descend into the earth to be punished for a thousand years, after which they would be reincarnated. One of the epistles of Peter borrows the concept of tartarus as a prison in order to describe what God did with the ancient angels who sinned; they've been imprisoned. John borrows the concept of tartarus (referring to it as the 'bottomless pit') to describe the imprisonment of the dragon, satan.
Gehenna should be translated as the Valley of Hinnom. This was a valley near Jerusalem, and appears to have held this name perhaps as back as the time of Joshua. This valley was used by the more idolatrous kings of Judah as a place where they would sacrifice their own children to the god Moloch. It may also have been the location where, in a single night, the Messenger of Yahweh killed a massive number of Assyrians from the army of Sennacherib. Going from there, it was traditionally associated with the location Isaiah refers to in his final chapter ('they shall go out' implies exiting Jerusalem into the valley), where dead bodies are devoured by unquenchable fire (i.e. fire that does not stop burning until it has completely consumed everything in its path) and undying worms (i.e. the maggots that unceasingly feast upon corpses). In ancient Aramaic translations of this chapter of Isaiah, the dead bodies are explicitly stated to be in the Valley of Hinnom, where the wicked suffered the 'second death'. Jesus confirms the traditional association by describing the Valley of Hinnom in the same way Isaiah describes the location filled with unquenchable fire and maggots.
The Valley of Hinnom is only ever used by Jesus (with a single, extraneous usage by James) when speaking to his fellow Jews. He uses it especially when warning them about sinning unrepentantly. Jesus uses the Valley of Hinnom because it had become a common symbol for God's divine punishment. In this sense, it is analogous to the lake of fire (especially since both are referred to as the 'second death'). According to Jesus, God is able to destroy both body and soul in the Valley of Hinnom.
Note: a little 'fact' is often thrown around that the Valley of Hinnom was a perpetually-burning garbage dump for the city of Jerusalem, where the bodies of dead criminals were thrown. As far as archaeological evidence goes, this is unproven. As far as textual evidence goes, the earliest this idea is mentioned is the 12th century AD. In the scope of this discussion, it is unreliable hearsay.