C.S. Lewis embraced Christianity in 1931 after years of identifying as an atheist.
His return to belief developed through conversations and friendships, especially with J.R.R. Tolkien and Hugo Dyson. Lewis had already begun moving away from atheism toward theism before accepting Christianity. He later described this period in autobiographical works including Surprised by Joy.
Lewis’s conversion transformed the direction of his writing. He became one of the twentieth century’s most prominent Christian apologists, producing works such as Mere Christianity, The Problem of Pain, and The Screwtape Letters. His fiction also frequently engages with religious themes, although it does so through different genres and degrees of symbolism.
The exact sequence of his intellectual changes can be described in stages rather than as one single moment. Nevertheless, 1931 is the standard year associated with his conversion to Christianity. This date is distinct from 1929, when Lewis moved from atheism toward belief in God.