CS Lewis is one of the great modern Christian writers. His writings are non-denominational, and can be appreciated by people of any faith. This box set contains some (though not all!) of his best work.
'Mere Christianity' is a great introduction to Lewis's way of thinking. Originally a series of radio addresses, this work details why Lewis is a Christian, and presents a case for Christianity that is compelling, to say the least.
'The Screwtape Letters' is my personal favorite. It is fiction, written from the unique point of view of a master devil named Screwtape. The master is trying to teach his nephew how to win souls for the devil through temptation. This one will definitely change the way you look at sin.
'The Problem of Pain.' -- what is pain? Well, Lewis tackles this subject here, and argues that God gives us pain because he loves us, and in order to mold us to his will.
'A Grief Observed' is a very intimate work, written after Lewis's wife died. It is, quite simply, a very honest and unique look at grieving, which shows this master Christian apologist, who seems to always have all the answers, vulnerable and without a solution.
'The Great Divorce' is Lewis's 'Divine Comedy.' This is a great look at Heaven and Hell, and presents the very compelling idea that people will go to Hell, not because they are forced to, but because they simply won't tolerate Heaven.
'Miracles' examines the question "can miracles occur?" For Lewis, the answer is yes, and this book shows how the Creator of Nature and mankind can work miracles without interrupting the 'natural' flow of things.
Buying these books together in a set is a good way to get these six classics at a great price. This is a wonderful starting point for anyone interested in Christian theology. No one interested in Christian thinker should be without these masterpieces by CS Lewis.