In this book Bart Ehrman attempts to provide the theological road-map whereby Jesus started out as a Jewish apocalyptic prophet and ended up having the high Christology of the historic Nicaea Creed (solidified by the Council of Constantinople in 381). As a historian he does not believe Jesus was God in any sense, or that he arose from the dead. He's merely being a historian telling us what he thinks is more probable than not.
In Ehrman's previous works he has argued that Jesus was an apocalyptic prophet who predicted the end of the known world and the coming of the Son of Man in his generation who would subsequently rule over the re-created world. Most scholars seem to agree with Ehrman, but others disagree with this view of Jesus, most notably Geza Vermes, Burton Mack, Marcus Borg, John Dominic Crossan, Stephen Patterson, Bruce Chilton, John P. Meier, Gerd Thiessen, Elisabeth Fiorenza, S. G. F. Brandon, Morton Smith, Reza Aslan, along with mythicist scholars Richard Carrier and Robert M. Price. Some of these different views of Jesus would require a different road-map to get to the high Christology of the fourth century, especially the mythicist view. So from the very beginning as we travel this map there are these obstacles.
Passing over those disagreements though, Ehrman's map seems to me to be a fairly standard mainline one which I've read in other works. Michael Coogan, John Collins and Paula Fredriksen probably agree with Ehrman since they wrote blurbs for it. Robert Funk, the founder of the Jesus Seminar, in the last chapter of his book "Honest to Jesus," says some of the same things.
Regardless, I'm very glad Ehrman wrote it. It's written so that the general populace can understand it. He has a way of communicating these ideas very well. Included are personal stories that may help readers know more about him as he considered this road-map in the first place. Several times he tells the reader he didn't at first agree with this or that idea, only to embrace it later. He describes himself as an "agnostic" now (p. 354).
In this brief review I've decided to tell readers a bit about how he argues so people can decide for themselves whether to buy it or not. My 5 star recommendation is based on his knowledge, communication skills and the fact that his views should be dealt with. In other words, this book shouldn't be ignored. It will be discussed in the years to come. Already there is one book length response by conservative Christians.
In the first chapter Ehrman tells us there were several divine humans believed to exist in ancient Greece and Rome. There was Apollonius, whom he goes in some depth about since his life parallels the life of Jesus. Then he tells us of gods who became human, like Philemon and Baucis (cf. Acts 14:11). There are divine beings believed to be born of both a god and a mortal, like Alexander the Great and Hercules. There are even humans believed to be divine, like Romulus, Quirinus, Julius Caesar and Caesar Augustus.
Ehrman shows us there were lots of gods, and that according to the beliefs in those early first century days "they were graded levels of divinity" (p. 39). This was a new thought to him, as it is to me. One can construct this as a divine pyramid with one great god at the top tier (according to some beliefs) and several tiers below, all of which were inhabited by divine beings. Just below the top tier were the great gods within each pantheon, then below that tier many other local gods and goddesses. At a still lower level were the demonic beings. On the lowest level were believed to be divine humans (perhaps demigods if you will).
In the second chapter Ehrman shows there were possibly divine humans in ancient Judaism. The first commandment, after all, doesn't deny other gods existed, only that the Israelites were to worship Yahweh. There were the Nephilim of Genesis 6, offspring of the sons of god who had sex with the daughters of men. The "Angel of the Lord" was believed to be a divine human being, as were kings, (Psalm 82) and angels ("the Watchers"). There was Daniel's "son of Man," and divine hypostases (an attribute of God that takes on its own essence) like Wisdom itself. Erhman argues that given these traditions it wouldn't be that much of a stretch to think of Jesus in the same terms as divine. We see it especially in the Gospel of John who described the pre-incarnate Jesus as the "Word" that became flesh (i.e., Logos).
In chapter three Ehrman argues that Jesus thought of himself to be the Messiah, but he did not claim to be God. Ehrman thinks when Judas betrayed Jesus he also told the authorities Jesus was claiming to be the Messiah. After all, that was what he was accused of, claiming to be the king of the Jews, and what he had to deny at his trials if he wanted to escape death on the cross. After Jesus died we find his Jewish disciples proclaiming he was the Messiah, even though "no Jew before Christianity" thought of a dying Messiah. Says Ehrman, "The only plausible explanation is that they called Jesus this after his death because they were calling him this before his death."
In chapter four Ehrman provides good strong reasons why Jesus did not rise from the dead using the tools of the historian, which are the only reliable tools we have at our disposal. If those tools cannot do the job then it cannot be done at all (faith has no method, correct?). In chapter five Ehrman tells us what historians can know. They can know that some of Jesus' followers believed he arose from the dead due to visions of him after his crucifixion, and that "this belief led them to reevaluate who Jesus was, so that the Jewish apocalyptic preacher from rural Galilee came to be considered, in some sense, God." (p. 174). His disciples concluded that Jesus was exalted to heaven. God had taken him into the heavenly realm "to a position of virtually unheard-of status and authority." (p. 205). "Jesus now had been exalted to heaven and is the heavenly messiah to come to earth. In an even more real sense, he was God. Not God almighty, of course, but he was a heavenly being, a superhuman, a divine king, who would rule the nations" (p. 208).
Ehrman calls this "exaltation Christology" and it took hold early on in the minds of his disciples. "It was because of his exalted status that Jesus was deemed worthy of worship" (p. 235). When Mark, the first Gospel was written, we read that Jesus was God's Son at his baptism. Later gospels kept placing his divinity further back in time. Jesus was believed to be divine at birth in Luke. The gospel of John, written last, says the Logos that became flesh was always divine. The Logos became incarnate in Jesus. Paul's conception of Jesus shares that of the gospel of John whereby we see an "incarnational Christology." It surely developed from exaltation Christology quicker in the mind of Paul than others, but that's how it developed for them all, Ehman seems to say.
By the time of the fourth century "many of the great thinkers of the Roman world had come to believe that a huge chasm separated the divine and human realms. God was 'up there' and was the Almighty. He alone was God." (p. 43) Gone was the pyramid of gods. So Ehrman argues, "One of the mistakes that people make when thinking about the question of Jesus as God involves taking the view that eventually was widely held by the fourth Christian century and assuming that this was in place during the early days of the Christian movement." "Jesus became God in that major fourth-century sense. But he had been seen as God before that, by people who did not have this fourth-century understanding of the relationship of the human and divine realms" (pp. 43-44).
While there were plenty of controversies in the first few centuries over the precise nature of this Christology and how Jesus could be God that were not settled quickly, even at Nicaea, and continue today, Ehrman goes on to show the important role of Constantine in this debate by favoring Christianity over all other religions, especially Judaism, and even the council of Nicaea against other Christianities.