Hi Dan -
Interesting question. Obviously there are some lessons and parallels to be found for Christians in the Chronicles of Narnia, but, as Bill points out, the CoN are stories, not allegories.
I think the answer hinges on what Narnia is - is it heaven itself, or is it just another world? From the first mention of Aslan in The Lion, the Witch and the Wardrobe, he is seen as arriving in Narnia from somewhere else. We soon learn that his own country lies beyond the sea. So choosing between Narnia and our world would not parallel the choice we all must make between God and hell.
Aslan says to the first Telmarine who chooses to return, "It is well chosen. And because you have spoken first, strong magic is upon you. Your future in that world shall be good. Come forth." It seems clear that it is an amoral choice before the Telmarines, perhaps like one of us choosing to live in one city or another.
I do think it is a lesson in trust. The Telmarines had only Aslan's word assuring them that a good place lay beyond the door. The ones who show up badly in this passage are those who did not trust Aslan enough to stay in Narnia, but who were also suspicious of his offer of a new home.
It is also a lesson in the dangers of pride. The Telmarines who were reluctant to stay in Narnia were chiefly those who had been important under Miraz, and who would lose their power and prestige under Caspian. Those who were happy to stay in Narnia liked the place for its own sake, and were not concerned about their position in it.
I hope this helps. :)
