Mainly because I didn't want it to be predictable. I've had people come to faith in my books, some do, some don't, as in real life. I left Ollie unconverted but asking questions. Who knows what will happen in future novels (I don't), but conversion isn't necessary for a story to work and raise questions. I wanted unbelieving readers to feel, "Ollie, open your eyes!" Then say, "oh, maybe I should open MY eyes."