(Quick! Name that movie!)
Just kidding! But in all honesty, this is a really easy question for me. The Bible is the only book that changed my life.
I've read quite a few books in my lifetime, but none of those books brought my life into focus or helped me choose a path in life. They enrich my life, but when all is said and done the Bible is the only written word that has the power to help me be a better person.
So with that, I'm going to leave you with my favorite passage.
"Do everything without complaining or arguing, so that you may become blameless and pure, children of God without fault in a crooked and depraved generation, in which you shine like stars in the universe."