C.S. Lewis converted to Christianity in 1931 after a period in which he had described himself as an atheist. His return to belief developed through conversations and friendships with writers including J.R.R. Tolkien and Hugo Dyson.
Lewis first became a theist in the late 1920s and then moved toward Christianity. He later described the process in autobiographical works such as Surprised by Joy. His conversion took place while he was teaching at Oxford and before the publication of his best-known Christian apologetic books.
The year 1931 is sometimes confused with 1929, when Lewis became a theist, or with 1930, a year associated with important stages in his intellectual development. The distinction matters: Lewis’s movement toward belief was gradual, and his conversion to Christianity followed his earlier rejection of atheism.