C.S. Lewis experienced his major conversion to Christianity in 1931.
Lewis had returned to belief in God several years earlier, but his conversion to Christianity took place in 1931. He later described a decisive conversation with J.R.R. Tolkien and Hugo Dyson, followed by a change he associated with becoming a Christian. Lewis wrote that he accepted Christianity while traveling to Whipsnade Zoo with his brother Warren.
The change followed years of intellectual and personal movement. Lewis had been raised in the Church of Ireland but became an atheist during adolescence. His reading, friendships, and philosophical reflection gradually led him back toward theism and then Christian belief.
The year 1931 is distinct from his earlier return to belief in God, often dated to 1929. This distinction matters because summaries sometimes compress the two stages. After 1931, Lewis became a prominent Christian apologist, broadcaster, essayist, and author of works such as Mere Christianity and The Problem of Pain.