"Did Jesus Exist?" is a book by Bart Ehrman, a New Testament scholar and out-spoken agnostic-atheist. Despite his private ideological leanings, Ehrman does believe that Jesus was a real historical person, and that the NT contains reliable traditions about him.
To simplify somewhat, Ehrman's Jesus is the Jesus of the Gospel of Matthew, but even more Jewish and without the miracles. Thus, Ehrman actually has a rather "conservative" view of Jesus. To psycho-analyze an author you've never met is a risky business, but personally I suspect that Ehrman (a former evangelical Christian) still feels some kind of psychological connection to the Bible in general and the Gospels in particular. But then, the position he is arguing against could be connected to an equally strong psychological aversion to the very same scriptures!
As the title makes obvious, Ehrman's book is a polemic against a group of authors he dubs "mythicists", who claim that Jesus never existed. While most Bible scholars hold that the Jesus of the Gospels is at least "freely based on a true story", the mythicists claim that everything is made up. The Gospels are purely mythological, and hence similar in character to pagan legends about Hercules, Dionysius, Osiris, etc. A popularized version of mythicism can be found in "The Jesus Mysteries" by Timothy Freke and Peter Gandy. More scholarly versions are argued by Robert Price, Richard Carrier and others. (Incidentally, Sweden has spawned a native mythicist in the persona of Alvar Ellegård. So yes, this debate feels strangely familiar!)
Personally, I consider Ehrman's book to be a very mixed bag. He constantly attacks the mythicists by using "the argument from authority", claiming that virtually all scholars in the relevant fields reject their positions. Maybe they do, but so what? The majority can be wrong. Personally, I'm convinced that Jesus really did exist, but it's not completely irrational to take the opposite position. From a naturalist viewpoint, the Gospels make little sense, often contradict each other, all non-Biblical sources for Jesus are rather late, etc. Nor is it difficult to pinpoint ideological reasons for why most scholars affirm Jesus' existence. Many NT scholars are Christian, and even non-Christian scholars want to claim Jesus as their own. Would Western scholars care if somebody denied the existence of Siddharta Gautama or Muhammad? Probably not. But deny Jesus, and you got it coming! Feminists want him to be a feminist, Jews want him to be a Pharisee, the Jesus Seminar want him to be a party animal, and more traditional Christians want him to be...well, the Son of God. Nobody wants him to be non-existent. If you risk being crucified by both the establishment and the opposition, the more prudent course is silence. And if you just can't shut up, your only outlet would be some small atheist press. So what's all this stuff about "every scholar in the field agrees"?
In the end, even Ehrman is forced to actually argue his case when confronted with Price, Carrier and some other scholarly (!) mythicists. He does a good job debunking the claim that Paul never mentions a historical Jesus, the idea that Matthew and Luke are solely based on Mark, or the claim that no authentic traditions about Jesus exist in the Gospels or Acts. A particularly strong argument is the observation that the New Testament contains allusions to earlier creeds, which the NT writers no longer believed in. Thus, there are "adoptionist" passages, suggesting that Jesus didn't become the Son of God until his baptism in the Jordan. There are also statements suggesting that Jesus didn't become the Son of God until the actual resurrection. Both are compatible with Jesus being a real person, a real person who was gradually exalted to divine status after his death. Of course, the mythicists could always retort that it could be an evolving myth, but if the point of the Jesus myth is to create a Jewish mystery religion, it would be more logical to cast Jesus as a god from the start.
Ehrman also points out that the New Testament contains information which could be considered embarrassing by later generations of Christians: Jesus had siblings, his family rejected him, he was baptized by John, some of his prophecies don't seem to ad up, etc. Thus, this information could very well be true. Why else make it up? Another point pressed by the author is the title "king of the Jews", never used by Christians but pinned on Jesus by his accusers (including Pilate). This suggests that the accusations against Jesus were a real historical event. Why make up a title nobody is using?
Ehrman is also somewhat frustrated by what he calls "the scholarship of convenience", which he believes Price and other mythicists indulge in ever so often. If some passage from Paul or the Gospels seems to indicate a real historical Jesus, just declare the passage to be a later interpolation and move ever on, victoriously! Thus, Price believes that Paul's famous list of Jesus' resurrection appearances is a later forgery. But what is the evidence for such a claim? Ehrman doesn't see any. By contrast, there's good evidence that Paul's attack on women preachers *is* a later interpolation - the passage isn't part of the main text in an early manuscript.
On other points, I believe Ehrman's arguments are much weaker. Thus, he writes that nobody denied that Jesus was a real historical character until the 18th century. But what about the Gnostics? Was the ethereal, mutable, docetic Christ of the Gnostics a "real historical character" in the same sense as the Jesus of the Church Fathers? What about the heavily allegorical interpretations of Origen, or the secret gospels of Clement of Alexandria, a Gnosticizing Church Father? The Gnostics didn't have to "deny the historicity of Jesus" in the modern mythicist sense, if their inner circle was interpreting the scriptures as a myth anyway! It's also curious that Ehrman brushes aside the Wisdom of Solomon, with is eerie, passion-like scenario about the Son of God being condemned to a shameful death. He writes that the Wisdom of Solomon never made it into the Jewish canon, but so what? Neither did the Book of Enoch, yet everyone agrees *that* scripture influenced early Christianity. Besides, the Wisdom of Solomon was included in the Septuagint, a Greek translation of the "Old Testament". Since there were Greek-speaking Jews and pagans even in Palestine, I don't think the LXX would have been unknown in Jerusalem.
I agree that Jesus was crucified - if Jesus really said or did what's in the Gospels, it's amazing he didn't end up dead much sooner - but the cross is also an ancient pagan symbol. Plato talks about the Son of God being suspended cross-wise in the universe, a statement later appropriated by Justin Martyr to prove that Christianity was "perfected Platonism". And while crucifixion was indeed a shameful death, there were exceptions to the rule. Even Christian theologian Martin Hengel admits that the Roman hero Marcus Atilius Regulus was sometimes said to have been crucified by the vile and treacherous Carthaginians. Yet, he was revered as a kind of pagan saint! Ehrman also sidesteps the claim of the early Christian apologists themselves, that the mystery religions were in some ways similar to the rites of Christianity.
My (provisional) take on Jesus is that he really did exist, but that either his own message or the message of the earliest Church might have had some "Hellenistic", "Gnostic" or "pagan" traits. Somehow, I feel a bit left out of this debate! Incidentally, even if we assume that early Christianity was a strictly Jewish affair, Judaism itself had traits which any disinterested observer would suspect may have been pagan borrowings (or even pagan survivals, if we assume that Judaism was once polytheist). Why was Wisdom personified as a woman? Goddesses were popular in the ancient world. What about the angels acting as mediators between God and man? The angels are surely an outside borrowing, perhaps from Persia. And what about the Wisdom of Solomon? Middle Platonism, anyone?
I recommend "Did Jesus Exist?" to those interested in the thorny subject at hand. Both Christians and mythicists will be stung by Bart Ehrman, the secularized Plymouth Brother of Chapel Hill. Nothing wrong with that. We all need our boats rocked from time to time. However, I don't think this book "rocks" hard enough, so I'll just give it three stars. ;-)