C.S. Lewis’s conversion to Christianity took place in 1931.
Lewis had moved away from Christian belief during his adolescence and described himself for a time as an atheist. His return to Christianity developed gradually through reading, reflection, and conversations with fellow writers and scholars, including J.R.R. Tolkien and Hugo Dyson.
Lewis later wrote that he became a theist in 1929 and a Christian in 1931. His conversion did not immediately produce the public author known for religious broadcasting; that role developed later, especially during the Second World War.
The date is sometimes simplified as if Lewis experienced one sudden moment, but his own accounts describe a process. His conversion became the foundation for books such as Mere Christianity, The Problem of Pain, and The Four Loves, while also influencing the moral and theological dimensions of his fiction.