CS Lewis speaks of Naturalism in terms of developing TRUTH, determining how people believe, how thought works. It has absolutely nothing to do with Evolution, Intelegent Design or science. He is talking about Moral Systems and reasoning.
Unfortunately (or Fortunately) he was also prolific so smaller minds can always find something within the body of Lewis material to support their contention (sound like any other book?)
A more reasonable view (sticking to Miracles which is what Dembski is mining) might be:
This [i.e. the impossibility of a naturalistic account of reason] is best seen if we consider the humblest and most despairing form in which this could be made. The Naturalist might say, 'Well perhaps we cannot exactly see - not yet - how natural selection would turn sub-rational mental behaviour into inferences that reach truth. But we are certain this has in fact happened. For natural selection is bound to preserve and increase useful behaviour' But notice what we are doing. Inference is itself on trial: that is, the Naturalist has given an account of what we thought to be our inferences that suggests they are not real insights at all. If the value of our reasoning is in doubt, you cannot try to establish by reasoning. There can be no question either of attacking or defending it.
This is the old seperation between religion and science, between why and how. CS Lewis had no problem with Evolution or Science. They work to determine the Hows of the world. Religion deals with Why, not the how.
Aslan is not a Tame Lion