C.S. Lewis said he became a Christian in 1931 after years of spiritual searching.
Lewis had returned to belief in God by 1929, but his conversion to Christianity developed over the following years. In September 1931, he took a decisive step toward Christian belief, influenced in part by conversations with J.R.R. Tolkien and Hugo Dyson. Lewis later described this transition in autobiographical works such as Surprised by Joy.
His religious outlook became central to his writing. He produced apologetic works including The Problem of Pain, Mere Christianity, and Miracles, while also expressing Christian ideas through fiction such as The Chronicles of Narnia and the Space Trilogy.
The dates can be confusing because Lewis described several stages: he moved from atheism to theism in 1929 and identified as a Christian in 1931. Thus 1931 is the standard year associated with his conversion to Christianity, while 1929 marks an earlier change in belief.