His (C. S. Lewis's) work is not frivolous in the way that Tolkien is frivolous, though it seems odd to call a novel of great intricacy and enormous popularity frivolous. I just don't like the conclusions Lewis comes to, after all that analysis, the way he shuts children out from heaven, or whatever it is, on the grounds that the one girl is interested in boys. She's a teenager! Ah, it's terrible: Sex — can't have that. And yet I respect Lewis more than I do Tolkien.
Slate interview, 2015