If you plan to see the movie and want to be surprised, stop reading here because I'm going to give some things away.
I say again, STOP READING HERE!!
OK, so if you're still with me it means you don't plan to see The Book of Eli. The big question, of course, is what book the title refers to. The answer: the Bible. And not just any version of the Bible, but the New King James Version of the Bible. The movie takes you years into the future, after a nuclear holocaust has wiped out most of humanity, scorched the earth, left cities in ruins, and taken most everyone's hope away. The movie suggests that it had been at least in part a religious war, and the Bible was at the center of hostilities. Somehow every single copy of the Scriptures had been burned or destroyed - except one. Eli (Denzel Washington) managed to save that one copy from destruction, so he hid it away in his backpack and guards it with his life. He reads it daily and knows it by heart. Some time back he heard God's voice directing him to take his Bible across the country to the West. So obediently he packs up what few belongings he owns and starts walking across America - or what's left of it anyway. Along the way he meets up with assorted pagan bad guys and protects the book from theft and damage. He's an amazing sharpshooter and an accomplished martial artist who can handle a sword with deadly force.
While this is a religion-friendly film, it's definitely not family-friendly. A lot of blood gets spilled, heads and hands get severed and go flying, and the body count is very high. It's a dark, violent movie filmed without color to give it a post-apocalyptic tone. Not only that, some of the language is offensive. And, the Shyamalan-ish twist at the end of the movie is completely unbelievable - as if you could believe anything else up to that point.
But if you don't mind those things and decide to see the film, what you'll see is a movie with a message that Christians will appreciate: The Word of God is divinely inspired, authoritative, powerful, and life-changing. There's even a scene where Eli prays before a meal. It's a humble, sincere prayer that catches the attention and warms the heart of Eli's traveling companion (played convincingly by Mila Kunis).
Those are the positive elements. On the other hand, I don't remember the name of Jesus ever being mentioned. And at the end of the movie, when Eli finally gets to his destination, the Bible is placed on a shelf alongside the Koran and other religious texts, as if to say that at the end of the day, all religions are equally valid and will get you where you need to go. Also, at one point Eli sums up the entire Bible with the Golden Rule. So he completely misses the meaning of the Bible. The Word of God is not a book of maxims designed to help you get more out of life and become a nicer person. It is the revelation of Jesus Christ, our Prophet, Priest, and King. Every page, every story, every psalm, every proverb, every narrative reveals the Savior and our need of him.
Still, I'm willing to give mild kudos to whoever came up with the story. Perhaps some who discredit the Bible or never bother to read it for themselves will pick it up and find it to be the entryway to light (Psalm 119:130).