C.S. Lewis became a Christian in 1931.
Lewis had been raised in the Church of Ireland but described himself as an atheist for much of his young adulthood. His return to religious belief developed gradually through conversations with friends, reading, and philosophical reflection rather than through one isolated event.
He first returned to belief in God in 1930 and became a Christian in 1931. His discussions with J.R.R. Tolkien and Hugo Dyson were especially important in the period immediately before his conversion to Christianity. Lewis later described this movement in Surprised by Joy, though that autobiography focuses on his intellectual and spiritual development rather than offering a simple dated diary.
The year is sometimes confused with 1930 because that was associated with Lewis’s renewed belief in God. The more specific date for his conversion to Christianity is 1931. His later books, lectures, and broadcasts made him one of the twentieth century’s best-known Christian writers.