What 1940s C.S. Lewis book developed his wartime radio talks about Christianity?

Mere Christianity developed C.S. Lewis’s wartime radio talks about Christianity.

The talks were broadcast by the BBC during the Second World War, beginning in 1941. Lewis used clear, conversational language to explain basic Christian ideas to a broad radio audience rather than presenting a detailed defense of one denomination.

The material was revised and published in book form in stages. Mere Christianity became the best-known title associated with these broadcasts and remains one of Lewis’s most influential works of Christian apologetics.

The phrase “mere Christianity” refers to core beliefs shared across historic Christian traditions. The book therefore differs from denominational instruction, while still reflecting Lewis’s own Anglican background and theological arguments.