Actually, this is more of an extension of #1 and #2 from the existing list, but the argument runs thus: The Gospels constitute eyewitness accounts of the events they describe (the Virgin Birth, miracles, the Resurrection, etc.), and just as juries are able give credence to eyewitness testimony in a modern court of law, so we ought to give credence to the “eyewitness testimonies” of the writers of Matthew, Mark, Luke and John.
The answer to this argument, of course, is that it presents a false analogy. Eyewitness testimony is never (or should never be) taken at face value in a court of law until the credibility of the eyewitness has been satisfactorily established. This is far easier to accomplish with eyewitnesses who are still alive, and whose existence is itself a demonstrable matter of record, than with those who are either millennia-dead or who may not have existed at all. Moreover, the reliability of the Gospels themselves as documents of historical fact is dubious in the extreme.
Another problem with the argument is that it gives undue credence to what is actually a very weak standard of evidence. As Austin Cline points out, “Juries place a lot of weight on eyewitness testimony, but this is because people place a lot more emphasis on personal stories than impersonal scientific data as a general rule. It’s unfortunate that people can be convicted solely on the basis of eyewitness testimony and without any corroborating evidence, but it has happened.” Carl Sagan is famous for the maxim, Extraordinary claims require extraordinary evidence–a kind of corollary to Ockham’s Razor and Hume’s argument against miracles –and eyewitness testimony just doesn’t cut the mustard. It can’t, otherwise we would have to accept as fact a myriad of claims based on personal testimony, including alien abductions, UFO sightings, astral travelling, ghost sightings, tarot reading and so forth.