So I was thinking about how late Luke might have been written. In my view, it seems as though our current Luke is a reaction to Marcion’s possible correction of Matthew. If Luke is after Marcion, then who is the earliest witness to things in the gospel narrative(s) that are unique to Luke? This would be Justin Martyr.
There are a few clues that Justin was aware of Luke (courtesy of a table put together by Neil Godfrey).
1. Elisabeth is mother of John the Baptist (Dialog with Trypho 84) / Luke 1:57
2. Gabriel’s announcement to Mary; “Be it according to thy word” (DT100) / Luke 1:38
3. Census under Quirinius (DT78) / Luke 2:2
4. Circumcised 8th day (DT23,67) / Luke 2:21
5. Sweats drops of blood (DT103) / Luke 22:44
6. Appears to disciples in Jerusalem (DT 51) / Luke 24:36 [the other gospels have him appear in Galilee, the more Gentile of the two]
7. Ascended to heaven (Firs Apology 51, 46) / Luke 24:51
Justin also seems to be aware of the Protevangelium of James:
But when the Child was born in Bethlehem, since Joseph could not find a lodging in that village, he took up his quarters in a certain cave near the village; and while they were there Mary brought forth the Christ and placed Him in a manger, and here the Magi who came from Arabia found Him.
The bolded part — Joseph and Mary taking residence in a cave to give birth — is only to be found in the gospel of James:
17. […] And they came into the middle of the road, and Mary said to him: Take me down from off the ass, for that which is in me presses to come forth. And he took her down from off the ass, and said to her: Whither shall I lead thee, and cover thy disgrace? for the place is desert.
18. And he found a cave there, and led her into it; and leaving his two sons beside her, he went out to seek a midwife in the district of Bethlehem.
The gospel of James is dated to around 150 – 200 CE.
One thing to point out is that Justin never refers to any gospel names as we know them (according to Matthew, etc.), he just refers to them as the Memoirs of the Apostles and it seemed like some sort of gospel harmony. If this is the case, then it was probably a compilation of the most popular gospels written by then; one of which more than likely included Marcion’s.
Here is a nice rundown of Marcion’s gospel vs. Luke’s:
In my opinion, Marcion must have been active a lot earlier than what’s traditionally ascribed by his enemies as his period of activity (140s CE). They had a vested interest in showing that heresy started “late” and orthodoxy started “early” (this is also the time period when gospels start getting names of those assumed to be “orthodox”; which is also after Marcion). There had to have been enough time for Marcion’s influence to spread all across the Roman empire by the time Justin is writing in the 150s. Of course, I could be wrong, but for the sake of argument, I think Marcion wrote his gospel – and began spreading it around – in the 130s. This is enough time for Mark’s gospel to have been written in the late 1st century (as I argued there), Matthew to make corrections that start getting circulated, Marcion becoming aware of both, and them him writing his correction of Matthew.
Sometime between Marcion and Justin, the current Loukan birth narrative was added, one that’s independent of Matthew’s, but still feeding on traditions of a miraculous birth. What Greco-Roman hero didn’t have a miraculous birth in antiquity? Of course, another line of evidence would be the portion of Luke that’s not the birth narrative that shows evidence of being aware of Matthew. Courtesy of Mark Goodacre:
The same phenomenon of editorial fatigue occurs also in double tradition material, where the evidence suggests that Luke is secondary to Matthew. In the Parable of the Talents / Pounds (Matt 25.14-30 // Luke 19.11-27), Luke, who loves the 10:1 ratio (Luke 15.8-10, Ten Coins, one lost; Luke 17.11-19, Ten Lepers, one thankful, etc.) begins with a typical change: ten servants, not three; and with one pound each (Luke 19.13). Yet as the story progresses, Luke appears to be drawn back to the plot of the Matthean parable, with three servants, “the first” (Luke 19.16), “the second” (Luke 19.18) and, remarkably, “the other” (Luke 19.20, ο ετερος). Moreover, the wording moves steadily closer to Matthew’s as the parable progresses, creating an internal contradiction when the master speaks of the first servant as “the one who has the ten pounds” (Luke 19.24), in parallel with Matthew 25.28. In Luke, he does not have ten pounds but eleven (Luke 19.16, contrast Matt. 25.20).
Possible evidence that Luke (or Marcion) depended on Matthew. On top of that, this also gives time for the author of Luke to utilize the (relatively) recently published works of Josephus.
One last point, and back to Luke 22:44. Ehrman argues in “Misquoting Jesus” that all throughout Luke, Jesus seems completely in control – never becoming emotional. It’s only at Luke 22:44 where Jesus seems to show any emphatic display of emotion. This might be a sign of interpolation; and if it is an interpolation then this means it happened before Justin since Justin is aware of it. Jesus — as the Good God of Marcion — being in control, showing no emotion, and knowing what will happen seems to be a staple of Docetic Christologies. Lk 22:44 might have been inserted as anti-Marcionite along with the rest of the birth narrative.