This is from a New Yorker article by Adam Gopnik about C.S.Lewis. It's worth reading, especially for some of his comments about Narnia and Christian allegory.
I think as we begin December, the month of candles and wishes and dreams, that this says a lot about why Christmas (and Hanukah) can mean so much to those of us without anchored religious beliefs:
Atheists need ghosts and kings and magical uncles and strange coincidences, living fairies and thriving Lilliputians, just as much as the believers do, to register their understanding that a narrow material world, unlit by imagination, is inadequate to our experience, much less to our hopes.