Hypothetical question: If you were in jail for your faith, and your friend could sneak you the Bible, but could only sneak you one book, which book would you ask for and why?

I hope that this never happens to anyone, but we can't deny the possibility. Christians in other places in the world face this reality all the time.

For me, I would pick the Gospel of John. It covers the deity of Christ deeper than the other gospels, explains the way of salvation, and covers all the major events of Jesus' life. It covers the beginning and why Jesus is important. Lots of good doctrine and theology.