Symbolism, Imagery, Allegory
Chances are decent you've heard about the Bible—you know, that big book that you find in bedside tables in motels sometimes. In Revolver, the Bible is much more than a leather-bound book though—in this book, the good book holds the answers to life's questions for Maria and Nadya, the former who is Sig's birth mom and the latter who is his stepmother. So while the Bible in general might make you think of the big guy in the sky, in Revolver it should immediately make you think of mothers.
When the Bible comes up for Sig, it's almost always because he's remembering some bit of advice he's gotten from either Maria or Nadya. For example, at one point Sig thinks:
Always tell the truth. Never lie, for Satan uses lies against us. Turn the other cheek. Be good and peaceful and avoid the path to evil. Forgive your enemies and pray for them. (30.1)
Sounds simple enough, right? Not so much. Even though Sig wants to honor the rules his mom wholeheartedly believes in, he can't ignore the fact that his dad taught him that sometimes these rules aren't enough. Should we "turn the other check" (a.k.a. act peacefully) when someone breaks into our home with a gun? Can we forgive people who kill our friends and family? These are big questions that Sig thinks about in the book, and they come right up against the biblical lessons he's been taught by his mother figures.
As Sig grapples with the conflicting ideas of his parents, the Bible—and the messages it contains that Maria conveys to the boy—comes to represent ideological rigidity, and the dangers of black and white perspectives. Maria may be fiercely against violence, but this doesn't spare her in the end. And though it's speculation, it seems fair to wonder whether she may not have been killed by Wolff had she been armed when he came for her. The same, of course, can be said for Einar—had he not presumed violence would come, he may not have encountered it.
Either way, though, in the end the Bible stands as a symbol for Sig's parents. When he sees the Bible in the snow by his dad's stuff, he grabs it because:
The Bible felt like the last link to his parents. It had been his mother's pride, that beautiful black leather-bound book. (33.44)
The Bible belonged to his mother and was with his father when he died—it is the only tangible thing he can reach for that helps him feel connected to both of his lost parents. In this way, in the end the Bible symbolizes comfort, which is pretty fitting since word on the street is that it does the same for plenty of folks who read it.
Plus the Bible contains the treasure map that Sig, Anna, and Nadya use to find Einar's gold. Considering how meager their existence is at this point, and how rich they ultimately wind up after investing the gold, it's safe to say that this map leads the three of them to a sort of salvation—which is exactly what the Bible purports to do in the Judeo-Christian tradition.
Man, there's a lot of symbolic power packed into this one tattered book.