Bart Ehrman must be regretting his decision to take on the subject of Jesus mythicism. It's not that he's done so, but how he's done it. His book Did Jesus Exist? was a sloppy bit of work that did him scant justice. I'm still not convinced Ehrman has done much more than skim-read much of the material he critiques - particularly Doherty's Jesus: Neither God Nor Man.
It's not that the mythicists shouldn't be challenged; they clearly should. And if they're genuine scholars (as many of them are) they would surely welcome the engagement. But Did Jesus Exist? has turned out to be a disappointment all round, doing little more than stirring up a hornet's nest of largely justified indignation.
Now it seems he's also getting walloped from the historicist centre-ground. Both Stephanie Fisher and Maurice Casey (author of the somewhat stroppy and high-handed Jesus of Nazareth) have levelled some pertinent criticism at Ehrman's assunptions and insinuations. Jim West has the details. Interesting to note that Ehrman refused to allow this criticism to appear on his blog, calling it "mean spirited."
Which seems a bit rich given the approach he takes in his own book.
Jesus of Nazareth