Clive Staples Lewis will be remembered as one of the most important Christian thinkers of the twentieth century. He was born in Ireland in 1898, and the major part of his adult years was spent as a Fellow of Magdalen College, Oxford, where he taught medieval literature. It was in 1931 that he was "surprised by joy," Lewis's own description of his conversion to Christianity. A brilliant scholar and writer, Lewis used his talents to reach thousands through the printed and spoken word.
He and a group of friends (including J. R. R. Tolkien, author of Lord of the Rings) gathered once a week to share their writings. During those years Lewis produced his famous work The Screwtape Letters. In the early 1940s he delivered talks on various Christian topics over British radio. His fame grew throughout Great Britain and spread to the United States. Out of those talks came the book Mere Christianity, a penetrating work on Christian apologetics. Countless Christians point to this book as an essential part of their faith journey. If sales are an indication of popularity, then C. S. Lewis is one of the most popular Christian thinkers of the twentieth century.