The analogy is actually what I like about them. Because this is the point - the Bible wasn't written by wicked men. It has some objectionable things in it, but the teachings of Christianity are good values that apply to everyone whether you believe in God or not. I was raised a Christian, and am now atheist, but still I take much of my inspiration from Christian teaching. I will quote the Bible as readily as I will any philosopher.
Many people are put off the good teaching of the Bible by the fact it is tied to religion. What C.S. Lewis did with Narnia was to present those values and messages in a way that was accessible to all. I loved the latest Narnia film not only because it was a great film, but also because it has a message that is a message for everybody, not just those who believe in invisible masters. It's a more overtly analagous book/film than the others, because it lacks an antagonist. The enemy is the characters themselves. All of what is said in the film about temptation, self-worth, conquering your darker side, all these things are true to life, so do not dismiss them just because they are also true to religion.