C.S. Lewis became a Christian in 1931, according to his autobiographical account.
Lewis described his conversion as developing through several stages rather than happening as one simple moment. He returned to belief in God in 1929 and later moved from theism to Christianity in 1931. His conversations with J.R.R. Tolkien and Hugo Dyson were especially important in his understanding of myth, incarnation, and Christian faith.
Surprised by Joy, published in 1955, recounts much of this intellectual and spiritual journey, although it does not provide a simple diary-like chronology. Lewis’s conversion date is therefore often stated as 1931, while 1929 marks an earlier stage in his return to belief. This distinction helps explain apparently different dates in summaries of his life.