Anyone who ever read the works of C.S. Lewis would have had no doubt.
Yep. But, these books are actually good reads even for non-believers. To the non-believer, these books are just fictional thrillers. When I read these books as a child, I never realized there was a deeper meaning contained within. When I was in 6th grade many moons ago, I checked the whole series out of the school library for our Summer Reading Program, because I was into that sort of genre.