Seeing as we're already pulling away from the OSC references as we jump into Tolkien and C.S. Lewis.....
I usually hate the retrospective analysis of fantasy tales in this manner - not because I don't like people drawing a deeper meaning from books than the plot they provide, but because it tends to warp enjoyment of those books for newer readers.
I would classify myself an atheist but that does not mean I would not use Christian, Mormon or even Satanic themes in art that I produce whether that's a story, poetry, song etc... It doesn't mean I'm being preachy or forcing a religion down someone's throat. It means that those themes are useful to me in providing the work of art.
Taking C.S. Lewis for example, it seems quite harmless to me that he would use Christian mythology to create a fantasy tale. As a child reading the stories I didn't see the connection and even though I can now (with everyone shoving it down my throat how could I not), it just seems to be an interesting basis for a fantasy story. I haven't ever bothered to find out what he had intended with these stories and I do know he provided more obvious and deliberate Christian literature, but to me it just doesn't seem that relevant.