C.S. Lewis became a Christian in 1931 after a long period as an atheist.
Lewis's conversion developed through conversations with Christian friends, especially J.R.R. Tolkien and Hugo Dyson. He described himself as having returned to belief in God in 1929, and in 1931 he became a Christian. His conversion later shaped works such as Mere Christianity, The Problem of Pain, and The Chronicles of Narnia.
Lewis had been raised in an Anglican household but moved away from Christianity during adolescence. His conversion was not an immediate change into a particular church tradition; he later became an Anglican. Dates associated with his religious development are sometimes compressed into one event, so 1931 is the commonly cited year for his conversion to Christianity rather than the earlier date of renewed belief in God.