I greatly enjoy C.S. Lewis. I find him to be very insightful when it comes to religion and life. I always read his books pencil in hand because he always says something that stands out to me and deserves some underlining.
The Great Divorce is a fantasy look at Heaven and Hell. A quote from the preface says "If we insist on keeping Hell (or even Earth) we shall not see Heaven: if we accept Heaven we shall not be able to retain even the smallest and most intimate souvenirs of Hell." This book exemplifies types of Hell that could prevent us from accepting (or moreover being accepted into) Heaven.
He first gives you a look at Hell where it is a run down, never-ending town always at dusk, overall a dismal place. You then board a bus that takes you up and out on an excursion to Heaven. The book if from the perspective of one passenger as he experiences Heaven being fresh from Hell and as he watches his fellow passengers and their struggle with how they find Heaven. There is much to be learned by the struggles of the passengers and why they have no desire to stay in Heaven and leave Hell behind them.
After reading this book it makes reflect on myself and what little pieces of "Hell" I might be hanging on to. This book was a quick read (especially for a C.S. Lewis book based on religion) and well worth the reading.