When we begin to imagine and understand hell, we are so violently repulsed by the horror of the spectre of the lack of God's presence, that we quickly come to the realization that we do not belong there, and that we are in great need of God's presence. This should have the effect of us immediately calling out to God, and fleeing from the imagining of hell, with our realization that we weren't "really there," and that this imagination was but a futile, human attempt at imagining something which we couldn't possibly imagine in any realistic, vivid sense.
If we do not experience this, we are merely fooling ourselves in thinking that we have somehow imagined or conceptually grasped hell.
There are topics where our knowledge of A and B can lead us by inference to truths C and D. My point here is: that which we know - in no clear, and distinct manner from scripture about hell - should never lead us on to C and D unless we do so with great care and prayer, and when we discuss these things with others, this should also be characterized by prayer and care.
At times, our engaging in this debate about Rob Bell and hell was not adequately characterized by prayer and care, nor proper respect of our own finitude, and how these matters of such great importance utterly dwarf our imagination and reason - how they condition us, our thinking, and our thoughts - instead of us being able to produce cogent, rational descriptions of such things.
So I'd say, for hell especially, when we teach about this topic, and think about it, let us be especially solicitous in using Christ's own words and those of the apostles - without engaging in too much "embroidering" upon them. These words should be enough. The Holy Spirit will convict as necessary, without our having to rub people's noses in the awful fate of what awaits them in the unredeemed state.
When Jesus was on earth, and demons proclaimed His name ... He told them to shut up. It is interesting to note how Jesus seems to not have wanted people to learn about Him from demons, even if what they said was true. If Jesus did not want people to learn truth about Him from demons ... how much more dangerous is it for us to pretend to learn about God from hell, when our very imaginations of hell are more likely to be conditioned by our own dark fantasies and nightmares, as we are really totally unable to imagine hell, since hell is so tied up with ultimate judgment, which is one of “God’s things” and not ours?
It's possible that further reflecting about the place of hell in cognition, imagination, and theology could help bring peace to the still-divided "pro-Bell" and "anti-Bell" camps. Perhaps hell is something where we more profitably reflect about the reflection, than try to reflect directly (except, of course, in reflecting upon Christ's own words and those of the apostles).
A few notes on things which make it impossible for us to conceptually or imaginatively grasp hell:
1) Agency (what we do, what we are responsible for) is never a “simple” question - it is a complicated issue. I hit your car, your car rams into the car in front of it. Did “you” ram into that car, where is the agency, who is responsible? When God created man - God gave man freedom and agency. This alone is a thing which is in many ways beyond our imaginitive and conceptual grasp - God's creation of moral agents, and the awesome (and terrifying) responsibility which belongs to such agents - which God could not withdraw from these agents, without their ceasing to be agents (and, perhaps - in doing so - corrupting justice - though I would add, even trying to imagine such is so far removed from human comprehensibility, that this notion also resists cognition and imagination).
2) Our abilities to think and imagine, and everything about the world in which we do so, are suffused with God’s natural grace, ordered according to His will. This is why we can think, talk, etc. etc.. We have no knowledge of what God’s natural grace will be like in hell. Or what “is left over” if we are in absence of such grace. What a person who is “in hell” is, for us, a rather meaningless thing other than what we are told in Scripture.
(Note: some philosophically-inclined readers might read in this something of Kant's notion of the sublime in aesthetics. This is a posting for more of a popular audience so I won't comment on that here, but comments on this are welcome)