There has long been the observation that Luke-Acts contains numerous parallels with the works of Josephus, generating three different theories to account for this: that Josephus used Luke, that Luke used Josephus, or that they both used some common but now lost source. Steve Mason has reviewed the arguments [1] and in summarizing the evidence concludes that, besides generic parallels of genre and form and the use of identical historical events, which are inconclusive as proofs, the "coincidence ... of aim, themes, and vocabulary ... seems to suggest that Luke-Acts is building its case on the foundation of Josephus' defense of Judaism," and therefore that Luke is consciously and significantly drawing on Josephus to supplement his use of Mark and Q and to create the appearance of a real history, a notable deviation from all the other Gospels which have none of the features of a historical work.
This thesis, if correct, entails two things. First, it undermines the historicity of certain details in the Christ story unique to Luke, such as his account of the Nativity, since these have been drawn from Josephus, who does not mention them in connection with Jesus, and thus it is more than possible that they never were linked with Jesus until Luke decided they were. This does not prove, but provides support for the view that Luke is creating history, not recording it. Second, it settles the terminus post quem of the date Luke-Acts was written: for in order to draw material from the Jewish War, Luke could not have written before 79 A.D., and could well have written much later since the rate of publication in antiquity was exceedingly limited and slow, requiring hand copies made by personal slaves (though at first oral recitations would be more common than written copies); and in order to draw material from the Jewish Antiquities, as he appears to have done, Luke could not have written before 94 A.D., and again could have written much later for the same reason.
Since this thesis is of great interest to students of Christianity, secular or otherwise, what follows is a simple summary of Mason's argument. I shall abbreviate Luke-Acts as L, and the collective histories of Josephus as J, or individually as JW (Jewish War) and JA (Jewish Antiquities). Josephus also wrote an autobiography and a tract against Apion (a scholar hostile to Jews), but these shall not be included in the abbreviation J. When referenced, they shall be identified as Life and Against Apion respectively. Note that Mason only singles out the most impressive examples of a connection. Other authors have scrupulously collected a great many more, though their results will not be surveyed here.
(which do not prove anything in themselves but add to or support the firmer evidence)
(some of which afford firm evidence of borrowing, some not)
"More than any other Gospel writer, Luke includes references to the non-Christian world of affairs. Almost every incident of this kind that he mentions turns up somewhere in Josephus' narratives." Mason, p. 205
Among these stories or facts (and Mason only mentions some of many) are:
This is clearly part of [Josephus'] literary artistry. How did Luke, then, come to associate the Egyptian, incorrectly, with the sicarii? If he did so independently of Josephus, the coincidence is remarkable. It is even more remarkable because sicarii is a Latin term for assassins. Josephus seems to have been the first to borrow this word and make it a technical term for the Jewish rebels in his Greek narrative.That Luke should use the same word, and similarly conflate the Egyptian with the other impostors mentioned by Josephus in the very same passage as leading people into the desert , further signifies borrowing--that exactly these mistakes should be made is incredible if not the result of drawing (albeit carelessly) on Josephus.
Mason concludes with one overriding similarity of tactic between L and J that is unlikely to have been independently devised: both very cleverly paint their religions as respectable Graeco-Jewish philosophical schools. Some of these features:
Finally, L curiously never mentions the third school, the Essenes. Yet Josephus praised them above all. They also happened to be much like Christians in many respects. Mason advances the hypothesis that Luke intended the Christians to take the place of the Essenes--and certainly wanted to avoid competing with them--so that Christianity would appear to Roman readers as this very third school: the most like Greek philosophy, the most like Christianity, and the most praised by Josephus. We lack the data necessary to prove or refute this hypothesis, but it is worth considering in light of all the evidence so far. It certainly fits.
Luke almost certainly knew and drew upon the works of Josephus (or else an amazing series of coincidences remains in want of an explanation), and therefore Luke and Acts were written at the end of the 1st century, or perhaps the beginning of the 2nd. This also results in the realization that almost every famous person, institution, place or event mentioned in L that can be checked against other sources is also found in Josephus, so that efforts to prove the veracity of L by appealing to these checks is cut short by the fact that he appears to have gotten all this information from Josephus, and simply cut-and-pasted it into his own "history" in order to give his story an air of authenticity and realism. He could thus, for all we know, have been writing historical fiction--using real characters and places, and putting them in fictional situations, all dressed up as history--history with a message, and an apologetic purpose. We thus cannot really know what in L is true or false with regard to the origins of Christianity or the actions of early Christians, since these particular details are the most prone to manipulation for didactic, symbolic, politico-ecclesiastical and apologetic reasons, and have very little if any external corroboration (and no external corroboration from a non-Christian).
[1] Steve Mason, "Josephus and Luke-Acts," Josephus and the New Testament (Hendrickson Publishers: Peabody, Massachusetts, 1992), pp. 185-229; cf. Max Krenkel, Josephus und Lukas (1894) and Heinz Schreckenberg, "Flavius Josephus und die lukanischen Schriften," Wort in der Zeit: Neutestamentliche Studien (1980) pp. 179-209. Also related: Gregory Sterling, Historiography and Self-Definition: Josephos, Luke-Acts and Apologetic Historiography (1992).
[2] A direct inversion of detail can be evidence of borrowing, in a manner called "emulation" or "transvaluation," where the borrower deliberately inverts the order or message of the story or idea that he has borrowed. This is especially the case when the inversion or change so befits the author's message that his reason for inversion is overwhelming. In this case, Christianity by definition aimed at becoming a forward-looking break with the past, the end of the Old Covenant and beginning of the New. Thus, Luke's inversion of the Josephan order makes perfect sense and is therefore plausibly inspired by Josephus--it becomes a counter-Josephus, overtly defying his message and replacing it with a new one.
[3] There was a convention of naming one's patron, something entirely appropriate for an author of a monumental work whose efforts or publication would require a lot of money and interest to produce, but not at all necessary for a work so brief as L, and thus not as explicable. Though this may be another clue to the man's invention, it is still possible for Luke to have been inspired to his task by a real Theophilus and written specifically for his benefit.
[4] Epaphroditus is probably a real man (the name was common among freedmen, and Josephus knew many such men in the imperial household), though we cannot confirm who he could be. The name means "Touched by Aphrodite" and thus "Lovely" or "Handsome," and Theophilus could be a transvaluation of this name: Love of God is superior to physical beauty granted by a "demon" (pagan goddess) of lust. Note also that in Life 430 and Against Apion 1.1 Josephus also dedicates his work to the same Epaphroditus, even using exactly the same epithet as used by Luke of Theophilus, "most excellent" (kratiste), though this is possibly the formal address given to a member of the equestrian class. Compare also Luke's introduction of the Gospel with Josephus' conclusion of Against Apion (2.296). Since both these works were written on or shortly after 100 A.D., if Luke is reflecting them at all, this puts the date of L entirely after the 1st century, perhaps in the first decade of the 2nd century. However, this is entirely too weak an evidence.
[5] It was impossible in almost all cases to know what someone said on a distant occasion, and therefore it was accepted practice among readers and authors of the time to invent speeches, and it is certain that the speeches preserved in Acts, for example, are entirely of Luke's creation. No one would have expected otherwise. Clearly there were no written editions of the speeches (as they surely would have been preserved with Paul's letters), and oral memory is notoriously bad at recalling anything but the gist and occasion of such things, and even then is easily corrupted by intervening events that alter or distort memory. In the time of L and J, it was well understood and accepted that speeches would be used as vehicles for the author to convey his own ideas, but also that it was proper to create speeches according to what the author thinks would have been appropriate to the speaker and the occasion (thus giving them at least some justification for inclusion in a supposedly objective history).
[6] L could not do this as easily or thoroughly as J, since Christianity was actually new, and the wordspace to cover such apologetic exceptionally limited by comparison. Even so, besides the obvious use of a geneology for this aim, L makes double time by tying Christianity into Jerusalem as its rightful center and origin more than any other Evangelist (Luke 1:18, 2:41-51, 9:51, 13:33, 17:11, 19:11, 24:13, 24:18, 24:33, 24:47, 24:52; Acts 1:8, 1:12, 8:1, 8:14, 9:26, 11:22, 15:2, 16:4, 21:17-18), and by making a far greater effort to show how Christianity is the God-ordained evolution of Jewish belief (its forerunners are scrupulous Jews: Luke 1:6, 2:39-42; as were its founders: Luke 4:16; Acts 3:1, 15:20, 15:29, 17:2, 21:20-26; and Jews who do not convert are in error: Acts 2:23, 3:15, 13:45, 14:2, 28:27; other overt Jewish tie-ins unique to L, many emphasizing Jewish and thus Christian antiquity: Luke 14:1, 24:27, 24:44; Acts 2:16, 2:25, 4:11, 4:25, 5:34-39, 7:2-53, 8:35, 13:16, 21:20), two facts which borrow off of Jewish antiquity and respectability and make it Christian. Luke uses speeches and off-hand remarks to pack in a huge number of reminders that Christianity is a sect of Judaism (and thus should be treated as such). Incidentally, Luke also goes more out of his way than any other author to make the Romans out to be the good guys, shifting blame ever more on the stubborn Jews who fail to see that they are in error, that Christianity is the true Judaism (Luke 23:4, 23:14-15, 23:22; Acts 2:23, 3:15, 4:10, 5:30, 13:6-12, 17:12-17, 22:22-29, 23:10, 23:16-35; other enemy Jews: Acts 13:45, 13:50, 14:19, 17:5, 18:6, 19:9, 21:27). This is L as apologetic history, just like J.
[7] It is certainly a mere coincidence that the villain in Josephus' story, the author of the rebellion (and whose relative, Eleazar, concludes the war by calling for the suicides at Masada), is a man named Judas from Galilee, whereas the villain in the Gospel story is also a Judas from Galilee. This coincidence is not likely to be of Luke's creation--if anyone invented it at all, it was Mark (cf. my review of MacDonald linked in the side box above). But this coincidence might have inspired Luke to transvalue stories and themes from Josephus in the first place.
[8] Mason is wrong, I believe, on two arguments related to this issue. First, he argues that Luke could not be describing a real census, because it could not have been of the whole world, nor required such moving around, and it was not plausible that ancestral homes were the required counting points since everyone was of many households and would not arbitrarily choose one ancestor that was a thousand years ancient. I am more charitable to Luke. First, Luke says "the whole inhabited" with the noun suppressed, and thus may have meant Judaea rather than the usual "land" or "world" (he might also have misunderstood Josephus).
Second, I have heard that Egyptian census studies suggest that shepherds and other itinerants were in fact called to their ancestral or traditional homesteads for counting, which makes sense since there would be no other way to reckon their property, which consisted of mobile livestock (grazing land was often communal or public property). It is also a well known fact that even Roman citizens had to enroll in one of several tribes and were counted by tribe--though records made it easier to do such counting regardless of location, such convenient records did not exist for Judaeans, at least none so easily employed by Romans for such a purpose, and getting provincials to organize in registered places according to tribal association would be practical.
Third, despite intermarriage, a very ancient namesake could be preserved as signifying tribal membership (we employ last names to do the very same thing today). Indeed, these links could even be invented. This was the case for newly-made Roman citizens, who had to enroll in a tribe purely as a legal fiction, and no doubt similar practices were in place or could have been set up when Judaea was annexed.
All the details Luke "adds" to Josephus could well come from common beliefs or experiences with Roman censuses in Luke's own day, though it is also possible that he invented them--or crafted them by mistake, since it appears possible that Luke did not clearly read Josephus, but skimmed or overheard his works (he might even have heard Josephus himself recite the work in public, as was a common practice for authors), or read an epitome (a popular convention of the day) rather than the actual work, or, perhaps most likely for being most common, did not have the book on hand when he wrote and worked from an imperfect memory.
[9] And Luke puts Paul in dialogue with philosophers (Acts 17:16-34; he even quotes Epimenides and Aratus!), and is also peculiar for having most closely paralleled the death of Jesus with the death of Socrates, cf. John Kloppenborg, "Exitus clari viri: The Death of Jesus in Luke," Scriptures and Cultural Conversations (1992). It is also likely that the image of Jesus as Cynic philosopher, or influenced by Cynicism, stems from Luke's portrayal more than any other.