Thank you for reading and for your comment. Let us certainly dispense with nonsense. I’m writing these essays as a learner; I’m certain that I will make errors and I want to remain open to corrections and criticism. However, it does not seem that I have made an error here.
To your first point concerning Luke, I admit to not being an expert in the matter, so I may be mistaken, but Nisan is the first month of the Ecclesiastical Hebrew calendar. Count ahead eight weeks (to get to the Abijah cycle) and one lands in the 4th week of Iyar, which is around April-June. Count ahead six months to the conception and we’re in Marcheshvan, which is around October-November. And then nine months from there to Av, which is July-August. Even a generous two month margin of error to account for my unfamiliarity with this calendar system puts us in October at the latest. Also note that the shepherds were living in the fields at the time of year that Jesus was born (Luke 2:8), which seems unlikely in the early winter.
But let us suppose that I am mistaken and that the priesthood timeline is as you have quoted. Going off of that timeline presupposes that Luke’s gospel was an accurate historical account, which is unlikely, as it was written half a century after the death of Jesus by someone who spoke a different language than him, and who wrote with clear intent to portray Jesus as the savior of the gentiles (who, in Luke’s world, would have been overwhelmingly pagan), and not just of the Jews in particular. The gospels documented stories intended to convert people to Christianity, and if Luke’s intended audience was at all pagan, which seems to be exactly the case, then that timeline becomes evidence in favor of a shifted birthday, as those dates would have resonated more with at least a portion of the audience. Further to that, Luke was also the author of Acts, which gives the backstory of Paul, which brings me to your second point.
There were indeed Jews among the early converts to Christianity, but pagans as well, and more of the latter as one approaches the authorship date of Luke’s gospel. The books of the New Testament were, after all, written in Greek, the lingua franca of the ancient pagan world, rather than Hebrew or Aramaic. First Corinthians, a Pauline epistle, mention its addressees as being former pagans specifically, and all of the authentic Pauline epistles were written to Christian communities in predominantly pagan areas, all of which were established before Luke was even written. And the largest conversion to Christianity would certainly have been among the citizens of the (formerly pagan) Roman Empire between the First Council in 325, and 380 when it became the official religion.