What was C.S. Lewis’s first book-length work of Christian apologetics?

The Problem of Pain was C.S. Lewis’s first book-length work of Christian apologetics.

Published in 1940, the book addresses why suffering exists if God is good and powerful. Lewis discusses divine omnipotence, human freedom, sin, animal pain, hell, and the Christian hope of heaven. The work is an argument written before the personal losses that later shaped his writing about grief.

Lewis’s apologetic method combines philosophical reasoning with vivid examples and clear prose. He wrote for general readers rather than only for academic theologians, helping make complex questions accessible to a wide audience.

The book is often confused with Mere Christianity, which developed from wartime radio talks broadcast from 1941 to 1944 and was published in book form in 1952. Miracles followed in 1947. The Problem of Pain therefore comes first among these major apologetic books, although Lewis had already published other religious essays and imaginative works.