The BBC first broadcast the talks later collected as Mere Christianity.
During the Second World War, C.S. Lewis delivered a series of radio talks for BBC Radio. The broadcasts began in 1941 and continued in revised series through 1944. They were aimed at a general British audience rather than an academic theological audience.
Lewis later revised and combined the talks into the book Mere Christianity. The work presents what he called the “common” or central beliefs shared by many Christian traditions, rather than arguing for one denomination’s distinctive doctrines.
The book’s structure reflects its broadcast origin: many sections use direct, conversational language and develop arguments step by step. The broadcasts made Lewis widely known beyond Oxford literary circles and helped establish him as a public Christian thinker. The title Mere Christianity was adopted for the collected volume rather than used as the original title of every radio series.