This is the first book I've read by theologian Marcus J. Borg. If that name is familiar, you may remember him from the Jesus Seminar sometime back. Jesus seminarians got together and decided the truthfulness of Jesus' teachings through voting on colored beads. I never participated. I've just read about it, and it sounded a bit hokey.
Regarding Borg, he writes well. His views are easy for the non-theologian to understand. However you probably what some base of understanding with Christianity, or the book could be lost on you.
The primary premise of the book is making a case for reading the Jewish and Christian bible's through a historical-critical lens. This is the opposite of what many modern conservatives do. In fact, Borg makes a rather effective case that the conservative approach is really a rather recent approach. One starting with the Protestant Reformation.
One area Borg was very effective was when he made the case for using the term creation "myth," and what myth means to high education. Myth in this sense doesn't mean a nonsensical and untrue story. However in common English is does which is why religious conservatives at the laymen level, Jewish and Christian, see the term applied to the Genesis story they get incensed.
Keeping that though in mind, the author isn't directly questioning the truthfulness of the Jewish and Christian Bibles, but he does make the case many events like the creation story, Noah, Moses, etc. are potentially allegorical. And events especially around Jesus of Nazareth have been embellished and or changed.
Historically nobody read a bible, at least at the commoner level. They listened to it being read in synagogue or church. The bines of scrolls, the many books and letters, it was complex to haul all this around. That was until the printing press was invented and then everyone could get their own pressed copy.
While many of Borg's theological views are outside the conservative norm, where he really shines in my opinion is as a biblical historian. He was one of the early ones outspoken in how Christianity originally sprang from Judaism and how most authors of the New Testament were committed Jews. If your willing to take in much of what Borg is saying, you will learn a lot around how one side views things along with a pretty good history lesson. A worthy read for anyone interested in the subject matter.