C.S. Lewis publicly identified as a Christian in 1931 after his conversion.
Lewis had moved from childhood belief to atheism during his adolescence, but his religious views changed during the 1920s. Conversations with J.R.R. Tolkien and Hugo Dyson contributed to his renewed belief in Christianity, and Lewis described becoming a Christian in 1931.
His conversion did not immediately produce all of his later theological works. Lewis gradually became one of the twentieth century’s most prominent Christian writers, publishing books such as The Problem of Pain, Mere Christianity, and Miracles. He also used Christian themes in fiction, including The Chronicles of Narnia.
Some accounts describe stages in Lewis’s return to belief, including a move from atheism to theism before Christianity. For that reason, 1931 is the standard year associated with his conversion to Christianity rather than the beginning of every change in his religious thinking.