I'm having trouble explaining myself, so maybe an example of Lewis' text with an approximation of my response at the time will suffice. This clip was chosen because it was the last straw that prompted me to write an email to several friends to vent about the my issue with Lewis.

At first it is natural for a baby to take its mother’s milk without knowing its mother. It is equally natural for us to see the man who helps us without seeing Christ behind him. But we must not remain babies. We must go on to recognise the real Giver. It is madness not to.

I tend to get annoyed when an author throws a couple vague metaphors, then tells me that I ought to do something. I get even more annoyed when they tell me that I am insane if I don't follow their advice. At this point in the reading I actually shouted out loud "WHY!?"

Because, if we do not, we shall be relying on human beings. And that is going to let us down. The best of them will make mistakes; all of them will die.

Holy crap! Is Lewis psychic? Did he hear me back in time, screaming at him that his reasoning is not coherent to me? You might think so, but then you would have to explain why the followup was even less reasonable than the metaphors, and something of a non-sequitur. Granted, if you think really hard you can come up with a satisfactory response that threads all these thoughts together into a coherent chain. I've even done that myself while writing this comment. But at its core, Lewis is arguing something here: that nothing good that comes from people actually comes from people, and that we must thus treat all beneficial things as acts of god. He goes on to hedge this claim with some nice words.

We must be thankful to all the people who have helped us, we must honour them and love them. But never, never pin your whole faith on any human being: not if he is the best and wisest in the whole world. There are lots of nice things you can do with sand: but do not try building a house on it.

He's like someone in an asylum briefly realizing that he's not actually Napoleon, and then imagining himself on a horse because he likes the idea of it more than being in a padded cell. But yes, there you have it. You can't rely on anything in this world because things break down and shit happens, and therefore you must rely on fiction. Because we all know fiction will get you to where you need to be.

I could go on, if you want, but I think this is getting a bit long for a single comment.