Oh really? The Masoretic text is the only authoritative text? Then I suppose the Masoretic reading of “like a lion my hands and feet” in Psalm 22 is correct, instead of the Septuagint “they have pierced my hands and feet”? And why do the New Testament books and epistles seem to be quoting from the Septuagint?
The Septuagint was translated by and for the Hebrews of the diaspora prior to Christianity, and it was *the* translation preferred by the early Church. The Masoretic text bears evidence of having been tampered with to refute Christianity. That doesn’t mean we can discount it entirely, but it is flagrant nonsense to say that it is the only usable translation.
And no we do not know Christ’s date of birth. If we, in this day and age, can calculate it with “complete certainty”, then tell me why in antiquity they were so unsure about the exact date—when the calendars were still in operation then and they were much closer to the events described? Do you think the early Christians were that dumb, that they couldn’t figure it out for themselves if it was as easy as you claim?
Because Greek was the language of most of the literate of that era. Hebrew was for the priests primarily.
"If we, in this day and age, can calculate it with “complete certainty”, then tell me why in antiquity they were so unsure about the exact date..."
You're speaking of the Romish church that rejected prophecy because they rejected Israel, about whom all prophecy was written. If you too reject prophecy in understanding these events, then don't waste my time replying to me. The Lord's apointed times tell all of God's events, to the minute. His word tells us that is what the stars are for; figure it out.