We knew C.S. Lewis was brilliant and The Screwtape Letters (affiliate link) only confirms it. How did Lewis even come up with this book? God only knows.
Screwtape is a devil who is teaching his nephew, Wormwood, how to tempt a young man (a British man named The Patient in the book). The book educates you and shocks you about the way demons look at us humans. Very insightful indeed.
Every letter becomes a chapter which advances the story of the young man. This is a small book and the chapters (or letters) are short. As such, The Screwtape Letters is very easy to read.
The ending will give you chills. Throughout the book though, depending on how much you already understand about the battle between Jesus and Satan, you will have goosebumps.
Teenagers should read this book for themselves, in my opinion. It would help them gain an understanding of the forces at play in their lives as they make decisions.