Chris over at Thoughts on Antiquity brings up some questions concerning the Testimonium Flavianum in his The Quest for the Historical Jesus, pt. 3. Especially helpful for background on this sticky wicket is the link to Peter Kirby’s page on the Testimonium.
I come down on the side of those who would declare it partly original to Josephus, but reworked by a somewhat inept, if pious, Christian hand. My reasons are these.
The passage has certainly been doctored, but originally a very negative evaluation of Jesus was included in the place of the Testimonium. This is indicated by the following tales of religious impostors (Decius Mundus in 18.3.4[65-80]; the Jewish defrauder of Fulvia in 18.3.5[81-84]; the Samaritan of 18.4.1[85-87]). Rather than looking at these as general “tumults” (Mason as quoted on Kirby’s page), I think it’s much more likely that we’ve got a series of specifically religious impostors described here, and that this is the unifying theme of this particular digression (notice the text goes from Jesus in the early thirties through the Samaritan incident in 36, which led to Pilate’s recall, then through Vitellius’s governing of Syria and the death of Tiberius in 37 A.D., only to revert to 34 A.D. after the digression is over in 18.4.6 with the death of Philip.). This digression is more easily connected by the theme of religious impostors than by the theme of Pilate or Tiberius.
The 10th century Arabic version of the Testimonium, preserved in the Book of the Title of Agapius of Hierapolis/Mabbug, is clearly more along the line of a paraphrase than a translation of Josephus on the part of Agapius. The order of elements is altered, and some of these are part of the “Christian additions” that others posit, making this a clearly more complicated case. Meier notes this in Marginal Jew, vol. 1, pp 78-79, n. 37. Like Kirby, I find the Agapian addition “Pilate condemned him to be crucified and to die” to be polemically directed against the Mohammedan [I prefer that term] assertion that Jesus was not crucified, nor did he die, as supported by the Kuran: “And their saying, ‘We did kill the Messiah, Jesus, son of Mary, the Messenger of Allah;’ whereas they slew him not, nor crucified him, but he was made to appear to them like one crucified; and those who differ therein are certainly in a state of doubt about it; they have no definite knowledge thereof, but only follow a conjecture; and they did not convert this conjecture into a certainty. On the contrary, Allah exalted him to Himself” (al-Nisā 4:158-9). It would certainly be appropriate for Agapius to be involved in such polemics with the spread of Mohammedanism [another preferred term], as it was just then making its permanent inroads into Asia Minor at the expense of Eastern Christian communities there (see Ostrogorsky, History of the Byzantine State, or Bat Ye’or, Decline of Eastern Christianity Under Islam). Overall, the changes in order, and thereby emphasis, of the elements of the Testimonium as found in Agapius in comparison to the typical text clearly indicates some textual reworking going on in his use of the text. It’s certainly not a neutral text preserving the original of Josephus.
Contra Meier, and most others it would seem, I would suggest that the original is almost wholly lost, and the Testimonium as it stands is in a highly altered form from the original, with positive terms replacing negative, but also likely shortened. This elimination of some phrases would explain some of the peculiarites of language in the passage as noted by Mason: these are reworked fragments of the original sentences, not very artfully used. As it almost certainly was wholly offensive to early Christians, the original was altered sometime in the second or third century, before it came to Eusebius in the form we also now have it in our copies of Josephus.
On the other reference, I see absolutely no reason to doubt the “James, brother of Jesus the so-called Christ” of 20.9.1 to be authentic. It’s completely neutral, but also relies upon the presence of some prior introduction of “Jesus” in association with the term “Christ.” So, of course, if someone rejects the Testimonium altogether, they must reject this reference as well, but it’s not necessary from the context. Relatedly, the context doesn’t hold what some of those who reject this reference have claimed. The objection in 20.9.1 is raised not that innocent men have been executed, but that the law was subverted by the high priest ordering the execution of the “lawbreakers” James and company, taking advantage of the absence of the Roman authority. The misreading is easily done, however, taking into account an unconscious harmonization of the book of Acts’ picture of James and the account of his death as related by Hegesippus via Eusebius.