Mere Christianity is a theological

Theology

Theology is the systematic and rational study of religion and its influences and of the nature of religious truths, or the learned profession acquired by completing specialized training in religious studies, usually at a university or school of divinity or seminary.-Definition:Augustine of Hippo...

 book by C. S. Lewis

C. S. Lewis

Clive Staples Lewis , commonly referred to as C. S. Lewis and known to his friends and family as "Jack", was a novelist, academic, medievalist, literary critic, essayist, lay theologian and Christian apologist from Belfast, Ireland...

, adapted from a series of BBC

BBC

The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...

 radio talks made between 1941 and 1944, while Lewis was at Oxford

University of Oxford

The University of Oxford is a university located in Oxford, United Kingdom. It is the second-oldest surviving university in the world and the oldest in the English-speaking world. Although its exact date of foundation is unclear, there is evidence of teaching as far back as 1096...

 during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. Considered a classic of Christian apologetics

Christian apologetics

Christian apologetics is a field of Christian theology that aims to present a rational basis for the Christian faith, defend the faith against objections, and expose the perceived flaws of other world views...

, the transcripts of the broadcasts originally appeared in print as three separate pamphlets: The Case for Christianity (1942), Christian Behaviour (1942), and Beyond Personality (1944). Lewis was invited to give the talks by Rev.

The Reverend

The Reverend is a style most often used as a prefix to the names of Christian clergy and ministers. There are sometimes differences in the way the style is used in different countries and church traditions. The Reverend is correctly called a style but is often and in some dictionaries called a...

 James Welch, the BBC Director of Religious Broadcasting, who had read his 1940 book, The Problem of Pain

The Problem of Pain

The Problem of Pain is a 1940 book by C. S. Lewis, in which he seeks to provide an intellectual Christian response to questions about suffering...

.
Lewis, an Anglican, intended to describe the Christian

Christianity

Christianity is a monotheistic religion based on the life and teachings of Jesus as presented in canonical gospels and other New Testament writings...

 common ground.