Which 1955 book by C.S. Lewis recounts his conversion from atheism to Christianity?

C.S. Lewis’s 1955 book recounting his conversion from atheism to Christianity is Surprised by Joy.

Surprised by Joy is an autobiographical work that traces Lewis’s intellectual and spiritual development. It covers his childhood, his education, his changing attitudes toward religion, and the experiences of longing that he called “Joy.” In Lewis’s usage, Joy was not merely happiness; it was a sudden, intense desire for something beyond ordinary experience.

The book describes Lewis’s movement from childhood belief, through periods of atheism, toward Christianity. His conversion was gradual rather than a single simple event. He became a theist in 1930 and later embraced Christianity, influenced partly by conversations with fellow writers and scholars including J.R.R. Tolkien and Hugo Dyson.

Surprised by Joy is sometimes mistaken for Mere Christianity, but the two books have different purposes. Mere Christianity presents arguments and broadcasts about Christian belief, whereas Surprised by Joy is primarily a spiritual autobiography. The memoir ends before much of Lewis’s best-known public writing career.