C.S. Lewis became a Christian in 1931 after an earlier return to belief in God.
Lewis had moved away from Christianity during adolescence and described himself for a period as an atheist. He later returned to belief in God in 1929. His conversion to Christianity followed in 1931, after sustained conversations and debates with friends and fellow writers.
J.R.R. Tolkien and Hugo Dyson were especially important in discussions that Lewis later remembered as influential. Lewis’s conversion shaped the direction of his subsequent work, including essays, sermons, fiction, and books of Christian apologetics. He became one of the most widely read Christian writers of the twentieth century.
The dates are often compressed into a single event, but Lewis distinguished between believing in God and accepting Christianity. That is why 1929 and 1931 refer to different stages in his religious development.