The ancient Israelites have been called the least morbid of all ancient peoples. Unlike their former masters, the Egyptians, the Israelites did not obsess over what happened to them after death. (One could argue antipathy to their former masters lead to apathy on the afterlife.) They saw the afterlife as one big, vast gray place: Sheol. Basically everybody spends an extraordinary amount of time waiting for The Final Judgment, when God will resurrect some for...well, "something better" is about as explicit as the ancient Israelites got.
The rest would either be destroyed permanently or left standing around in Sheol forever.
Hell as we know the term got ret-conned into the OT by translators seeking to reconcile it to the NT, specifically Jesus' teachings on Gehenna. (A more accurate translation of Sheol into contemporary English would be "death" or "the grave".)
BTW, Gehenna is about as perfect an example of language / culture drift coupled w / folk theology as one could hope for. Gehenna was a valley used as a garbage dump just outside of Jerusalem; traditionally it was where human sacrifices to Moloch had been conducted. Thanx to brilliant & gifted writers & artists like Dante Alighieri, Michaelangelo Buonarroti, Gustave Dore, Heironymus Bosch, and Joe Martin, we have images like these --
-- when in reality a better, closer contemporary translation of Gehenna would not be Hell but “the unholy garbage dump”.
What is important to note is that Jesus had a specific teaching on Gehenna, that He viewed it differently from the way His fellow Jews viewed Sheol, that He thought it was important everybody be warned about this possible outcome so they could take steps in this life to avoid it, and that not everybody was going to avoid it.
And that 's not counting verses like Matthew 5:21-23 where Jesus refers to Gehenna (a trash dump outside of Jerusalem) as the final destination for the unjust & the unrepentant, or Mark 9:43 where He speaks of an unquenchable fire.
(I'm deliberated omitting the descriptions of Hell found in the Revelation Of John as that is an acknowledged symbolic vision, as well as any apostletic dissertations on the topic so I can focus solely on Jesus' direct teachings on the matter.)
Jesus' teachings cover these main points:
God wants everybody to share the afterlife with Him.
Everybody who wants to share that afterlife with God will.
There will be those who for any number of reasons will either ignore the invitation or not be ready when the time comes.
Merely following the various religious rules, rites, & regulations will not get you into the party.
Having faith in God's grace is good, but actually doing what God wants by showing justice & compassion is even better.
So the idea Rob Bell expresses, that sooner or later God will redeem even the most irredeemable souls, does not seem to be supported in a plain text reading of scripture.
If nothing else, it ignores the one unforgiveable sin: Believing that the Holy Spirit is evil ('cuz if you really believe that, you won't be asking God to forgive you since you will believe yourself to be morally superior to God; see Cthulhu).
This is not just a self-fulfilling prophecy, it’s one that also implies that Hell is not a creation of God.
If God didn’t make Hell, then who did?
 This, minus the judgment & resurrection, is a pretty common pagan view of the afterlife. Hades for the Greeks and Romans wasn't eternal torment but a bleak, tasteless, bland, boring existence. Yeah, some poor b/tards were being tormented for all eternity, but those were guys being tormented by a particular god for doing something that pissed that god off, not a final judgment and / or divine retribution. Since it was possible to do something that pleased Jove while pissing off Athena, it made acts of religious faith a pretty dicey affair for pagan polytheists. But I digress...
 Is that really a parable or is it journalism? Interesting that the poor man who makes it to paradise -- the only non-historical person to be named in a parable -- has the same name as Jesus' cousin, whom He resurrected from the dead.