Previously, at around age 15, [C. S. Lewis] became interested in the occult and began to actively and publicly define himself as an atheist. As such, he spent an inordinate amount of time thinking about God, explaining why God didn’t exist, and surrounding himself with like-minded people and things. The problem was that when he returned to Oxford and started paying attention to his experiences (and the way he felt as he read, wrote, and interacted with people), he found he was being (spiritually and emotionally) sustained and nurtured by things and people who were theistic as opposed to atheistic.