In order to appreciate the nature of Craig’s distortion, it is necessary to take a little more detailed look at what Sherwin-White wrote and its context.
What is to an ancient historian the most surprising in the basic assumption of form-criticism of the extremer sort (i.e., those who maintain “that the historical Christ in unknowable and the history of his mission cannot be written”(RLRSNT p.187)), is the presumed tempo of the development of the didactic myths—if one may use that term to sum up the matter. We are not unacquainted with this type of writing in ancient historiography, as will shortly appear. The agnostic type of form-criticism would be much more credible if the compilation of the Gospels were much later in time, much more remote from the events themselves, than can be the case. Certainly a deal of distortion can affect a story that is given literary form a generation or two after the event, whether for national glorification or political spite, or for the didactic or symbolic exposition of ideas. But in the material of ancient history the historical content is not hopelessly lost. (RLRSNT p.189)Sherwin-White is not saying that the extreme form-critics are demonstrably mistaken, he is saying that he, as a professor of Roman history, does not find their position persuasive.
It is important to remember that an authority in ancient Roman history is commenting on biblical form-criticism, an area of scholarship outside his field of expertise in which he considers himself “an amateur.” (RLRSNT p.187) However, he had just spent 185 pages discussing the extent to which the stories in the New Testament reflect what is known by scholars in his specialty. It is easy to imagine skeptics asserting that he was wasting his time because the Bible was just a bunch of myths. So Sherwin-White explained why he thought the biblical accounts were worthy of an historian’s attention, but he was not attempting a systematic refutation of the skeptics’ position because he was not an authority on biblical form-criticism.
I would liken Sherwin-White’s position to my own experience as a law school graduate who has not practiced law for almost fifteen years. When I hear someone express a bizarre opinion about constitutional law or contract law or criminal law, I might say something like, “Based on what I remember from law school, that doesn’t sound right to me.” However, I am not up to speed on the latest legal developments and I don’t consider myself qualified to make authoritative statements (especially since I no longer carry malpractice insurance). When it comes to the law, I consider myself an educated amateur and I am careful to express my opinion from that perspective. By the same token, Sherwin-White was offering an educated amateur’s take on form-criticism, not a thoroughly researched refutation.
Sherwin-White is certainly an extremely well-educated amateur and his opinion is worthy of great respect. In fact, however, his opinion was that the New Testament merited critical study in order to determine what could be known about the historical Christ. It is an opinion shared by many modern liberal scholars like those found in the Jesus Seminar. It is a position that I find persuasive as well (although my amateur status is beyond dispute).
I am very curious to know how Sherwin-White’s “[t]he agnostic type of form-criticism would be much more credible if the compilation of the Gospels were much later in time” became Craig’s” the rate of legendary accumulation would have to be ‘unbelievable’.” I would be particularly interested in hearing Craig’s justification for putting “unbelievable” in quotation marks when Sherwin-White never used the word and never purported to be making such a definitive statement. The failure to put quotation marks where they belong is known as plagiarism. The insertion of quotation marks where they don't belong seems equally dishonest.