Which C.S. Lewis book presents his radio talks about basic Christianity?

Mere Christianity presents C.S. Lewis’s radio talks about basic Christianity.

The book grew out of a series of BBC radio broadcasts Lewis gave during the Second World War. The talks were delivered in several groups between 1941 and 1944 and aimed to explain common Christian ideas in accessible language rather than defend one particular denomination.

Lewis later revised and combined the broadcasts into book form. Mere Christianity discusses moral law, human behavior, Christian belief, and the doctrine of the Trinity. Its title refers to the central beliefs shared by many Christian traditions, not to a new church or denomination.

The work is often confused with The Problem of Pain, another Lewis book concerned with Christian theology. The Problem of Pain focuses especially on suffering and divine goodness, whereas Mere Christianity develops a broader introductory case for Christian belief. Lewis’s conversational radio style helped make the book influential beyond its original wartime audience.