Which C.S. Lewis book is subtitled “A Case for Christianity”?

Mere Christianity is the C.S. Lewis book associated with the subtitle “A Case for Christianity.”

The phrase appears in the title history of the work that developed from Lewis’s BBC talks. An early printed version was issued as Broadcast Talks, and later editions used the title Mere Christianity, with “A Case for Christianity” associated with the first part of the collected work.

Lewis intended “mere Christianity” to mean the central beliefs shared across historic Christianity, rather than the distinctive doctrines of one denomination. That focus explains why the book discusses morality, belief, and Christian teaching without presenting itself as a guide to a particular church.

The title is often remembered more readily than its publishing history. The work was assembled from wartime broadcasts and revised for print, so its chapters preserve the direct, explanatory style of talks designed for radio listeners.