C.S. Lewis described himself as converting to Christianity in 1931. His return to Christian belief followed years of intellectual and personal change, including conversations with J.R.R. Tolkien and Hugo Dyson.
Lewis had abandoned Christianity during his adolescence and later became an atheist. He began moving back toward theism during the 1920s, influenced by philosophical arguments, literature, and friendships. In 1929 he became a theist, and in 1931 he returned to Christian belief.
Lewis later wrote that his conversion was not a single simple moment. He distinguished between becoming a theist and becoming a Christian, and he described the latter as occurring during a journey to Whipsnade Zoo in September 1931. His accounts emphasize that conversion involved both reasoning and resistance.
The year is sometimes confused with 1929 because that was the year Lewis said he submitted to God and became a theist. The two dates refer to different stages in his religious development.