Clive Staples Lewis (29 November 1898 – 22 November 1963) was a British writer and lay theologian. He held academic positions in English literature at both Oxford University and Cambridge University.He is best known for his works of fiction, especially The Screwtape Letters, The Chronicles of Narnia, and The Space Trilogy, and for his non-fiction Christian apologetics, such as Mere Christianity, Miracles, and The Problem of Pain. Lewis and fellow novelist J. R. R. Tolkien were close friends. They both served on the English faculty at Oxford University and were active in the informal Oxford literary group known as the Inklings. Lewis was baptised in the Church of Ireland, but fell away from his faith during adolescence. Lewis returned to Anglicanism at the age of 32, owing to the influence of Tolkien and other friends, and he became an "ordinary layman of the Church of England". Lewis's faith profoundly affected his work, and his wartime radio broadcasts on the subject of Christianity brought him wide acclaim.