...what is (or rather, was) admitted without argument by all scholars, is that the liturgical placement of Christmas is an arbitrary choice, not connected with any real birth date of Jesus, which nobody could possibly determine. Well, it really does seem as though the experts were all wrong; and I, of course, along with them. Today, thanks in part to the Qumran scrolls, we can establish it precisely: Jesus was indeed born on December 25. An extraordinary discovery indeed, and one which is beyond any suspicion of Christian apologetics, since it comes from a Jewish scholar from the University of Jerusalem.
Let us see how its complex but fascinating mechanism works. If Jesus was born on December 25, obviously he must have been conceived by the Virgin nine months before; and in fact, Christian calendars place the feast of the Annunciation to Mary by the archangel Gabriel on March 25. But we also know from the same Gospel according to Luke that six months earlier Elizabeth had conceived the precursor, John, who was to be called the Baptist. The Catholic Church has no festival day for that conception, but the ancient Eastern Churches celebrate it solemnly between 23 and 25 September; that is, six months before the Annunciation to Mary. A logical sequence, but one based on unverifiable traditions, not on events that can be placed at definite times. So everyone thought until our day; but in fact, it really looks as if it was not so.
We have to start from the conception of John. The Gospel of Luke opens with the story of the elderly couple, Zacharias and Elizabeth, resigned by then to being sterile – one of the worst disasters for a Jewish family. Zacharias belonged to the priestly caste, and one day, as he was on duty in the Temple of Jerusalem, he had a vision of Gabriel (the same angel who, six months later, will appear to Mary in Nazareth) telling him that, in spite of their age, he and his wife would have a son. They were to call him John, and he would be “great before the Lord “.
Luke takes care to mention that Zacharias belonged to the priestly class of Abhijah, and that when he saw the apparition, he was “serving in his class’ turn”. In fact, the sacerdotal caste of ancient Israel was divided into 24 classes which paid their service in the Temple in an unchanging order, twice a year for a week. It was already known that Zacharias’ class, that of Abhijah, was the eighth in the official list. But when did its service turns fall? Nobody knew. Well, by making use of research by other specialists, but above all by working on texts from the Qumran library, now the riddle has been broken by Professor Shemarjahu Talmon of the Jewish University of Jerusalem – as I mentioned. The scholars managed to show the exact order of the turns of duty of the 24 sacerdotal classes. That of Abhijah served in the Temple twice a year, like all others, and one of them was the last week of September. The Eastern Christian tradition that places the announcement to Zacharias between 23 and 25 September was therefore well-founded. But since Professor Talmon’s discovery, likelihood has turned into near-certainty, since other scholars, stimulated by his data, have tracked down the origins of the chronological traditions. They ended up concluding that it must have come direct from the earliest Jewish Christian community in Jerusalem itself. A memory as primitive as it has proved steadfast, as the Eastern Churches have shown in several other cases...
FPB adds: Two points. First, Luke's concern to note Zacharias' priestly caste is typical of his near-excessive concern with exactitude in places and dates, which has been shown again and again. Second, if the complex of dates for the conception and birth of John and Jesus can indeed be traced to the earliest Jewish Christian communities in Palestine, then it predates the Pagan festival which it is supposed to have imitated - Sol Invictus - by a couple of centuries. The cult and festival of Sol Invictus are not traditional in ancient Rome: they were established by innovating Emperors in the third century AD, and indeed, the earliest Roman state did not even have a cult of the Sun. It was first imported as a private cult by the Sabine family of the Auselii or Aurelii, and did not spread to official bodies until well into the Christian age. What is more, the Emperors who established it, Aurelianus and Gallienus, were very concerned by the growing power of Christianity and specifically worked to oppose it. So the question is: who imitated who?