What was the first book C.S. Lewis published after becoming a Christian?

The Pilgrim’s Regress was the first book C.S. Lewis published after becoming a Christian.

Published in 1933, The Pilgrim’s Regress is an allegorical novel about a character named John who undertakes a journey toward a distant country. Lewis wrote it soon after his conversion and used the story to explore religious belief, reason, desire, and the obstacles he believed modern people placed in the way of faith.

Lewis had returned to Christianity by 1931 after conversations and friendships involving figures such as J.R.R. Tolkien and Hugo Dyson. The book therefore stands at the beginning of his career as a Christian writer, before his best-known apologetic works and before the Narnia novels.

The title deliberately echoes John Bunyan’s The Pilgrim’s Progress, but Lewis’s book is not a retelling of Bunyan’s story. Its subtitle, An Allegorical Apology for Christianity, Reason and Romanticism, signals its intellectual and autobiographical concerns.