I doubt that any LW member would take all of his information about the value of atheism from Lewis. If you let yourself convince that atheism is wrong by reading Lewis than your belief in atheism was very weak in the first place.

I have a hard time imagine pushing anyone in LW into a crisis of faith about atheism in which we wouldn't come out with better belief system than he started. If someone discovers that he actually follows in atheism because it's cool and works through his issues, he might end up in following atheism for better reasons.