C.S. Lewis became a Christian in 1931 after returning to belief in God.
Lewis had moved away from Christianity during his adolescence and described himself for a time as an atheist. His intellectual and personal discussions with friends, including J.R.R. Tolkien and Hugo Dyson, contributed to a gradual change in his outlook. He first returned to theism and later embraced Christianity.
Lewis described his conversion as a process rather than a single uncomplicated moment. In Surprised by Joy, he famously wrote that in 1929 he admitted that God was God, and in 1931 he accepted Christianity. The dates therefore mark related stages in his religious development.
His conversion became central to his later public work. Books such as The Problem of Pain, Mere Christianity, and Miracles made him one of the twentieth century’s most widely read Christian writers.