It's a... collection of letters written by a senior demon named Screwtape to a junior demon named Wormwood containing valuable information on how to win and keep a man's soul. Regardless of the mythology you spout, the teachings in this book of how darkness, drama, laziness, hatred, cowardice, falseness, etc. keep up from laughter and light and mirth are invaluable. When reading it, consider that the context is placed firmly within the camp of Christianity and just... go with it for a while... until you start really listening to what Screwtape is saying and can apply it within your own beliefs. I'm not suggesting you follow his advice... LOL... quite the contrary. I'm suggesting you listen to what he is saying and try to recognize your OWN demon's efforts in your life.
The opening of the book has two quotes which I have come to adore:
The best way to drive out the devil, if he will not yield to texts of Scripture, is to jeer and flout him, for he cannot bear scorn. -- Luther
The devil... the prowde spirite... cannot endure to be mocked. -- Thomas More
Take that with you today and life will be a little better, I promise. :)