Which allegorical novel did C.S. Lewis publish in 1933 as his first Christian work after conversion?

The Pilgrim’s Regress was the allegorical novel C.S. Lewis published in 1933 as his first Christian work after conversion.

The book follows a character named John on a journey toward a distant land, using an imaginative landscape to explore Christian belief and objections to it. Its title deliberately recalls John Bunyan’s The Pilgrim’s Progress, but Lewis’s story is also shaped by his own intellectual and religious development.

Lewis completed his conversion to Christianity in 1931, after years of movement from atheism toward belief. The Pilgrim’s Regress was published soon afterward and therefore occupies an important place in his Christian writing. It is not the same book as Mere Christianity, which grew from wartime radio broadcasts, or The Problem of Pain, a nonfiction theological work published in 1940.