Two theories on why Christmas is Dec. 25

In simultaneous pre-Christmas cover stories, Time and Newsweek magazines sifted with skepticism the narratives of Jesus Christ’s birth in Matthew and Luke—the only accounts we have since no other chroniclers recorded the Nativity of this obscure peasant.
It’s far less important than those historical debates, but there’s also a small disagreement about why the church later chose Dec. 25 for Christmas. Two main theories compete.
One notes that in AD 274, the Roman emperor Aurelian inaugurated Dec. 25 as the pagan Birth of the Unconquered Sun celebration, at the calendar point when daylight began to lengthen.
Supposedly, Christians then borrowed the date and devised Christmas to compete with paganism.
Aurelian’s empire seemed near collapse, so his festival proclaimed imperial and pagan rejuvenation. Prior to 274, there’s no record of a major sun cult at the Northern Hemisphere’s winter solstice (the year’s shortest day, which actually occurs before Dec. 25).
Michael Tighe, a church history specialist at Muhlenberg College in Allentown, Pa., champions the exact opposite theory.
Aurelian almost certainly created “a pagan alternative to a date that was already of some significance to Roman Christians,” Tighe wrote last December in Touchstone, a Chicago-based magazine for Roman Catholic, Orthodox, and Protestant traditionalists.
True, the Christians later appropriated Aurelian’s festival into their Christmas.
But Dec. 25 “appears to owe nothing whatsoever to pagan influences,” Tighe asserted.
He said the pagans-first theory originated only three centuries ago in the writings of Protestant historian Paul Ernst Jablonski and Catholic monk Jean Hardouin.
Tighe acknowledged the first hard evidence of Christmas occurring on Dec. 25 isn’t found until AD 336—and the date only became a fixed festival in Constantinople in 379.
However, the definitive Handbook of Biblical Chronology by Prof. Jack Finegan (Hendrickson, 1998 revised edition) cites an important reference in the Chronicle written by Hippolytus of Rome three decades before Aurelian launched his festival.
Hippolytus said Jesus’ birth “took place eight days before the kalends of January,” that is, Dec. 25.
Tighe said there’s evidence that as early as the second and third centuries, Christians sought to fix the birth date to help determine the time of Jesus’ death and resurrection for the liturgical calendar—long before Christmas also became a festival.
The New Testament Gospels say the Crucifixion happened during the Jewish Passover season. The “integral age” concept, taught by ancient Judaism though not in the Bible, held that Israel’s great prophets died the same day as their birth or conception.
Quite early on, Tighe said, Christians applied this idea to Jesus and set the Passover period’s March 25 for the Feast of the Annunciation, marking the angel Gabriel’s announcement to Mary that she would give birth.
Add nine months to the conception date and we get Dec. 25.
Last year, Inside the Vatican magazine also supported Dec. 25, citing a report from St. John Chrysostom (patriarch of Constantinople who died in AD 407) that Christians had marked Dec. 25 from the early days of the church.
Chrysostom had a further argument that modern scholars ignore:
Luke 1 says Zechariah was performing priestly duty in the Temple when an angel told his wife, Elizabeth, she would bear John the Baptist. During the sixth month of Elizabeth’s pregnancy, Mary learned about her conception of Jesus and visited Elizabeth “with haste.”
The 24 classes of Jewish priests served one week in the Temple, and Zechariah was in the eighth class. Rabbinical tradition fixed the class on duty when the Temple was destroyed in AD 70 and, calculating backward from that, Zechariah’s class would have been serving Oct. 2-9 in 5 BC.
So Mary’s conception visit six months later might have occurred the following March—and Jesus’ birth nine months afterward.
“Though it is not a matter of faith, there is no good reason not to accept the tradition” of March 25 conception and Dec. 25 birth, the magazine contended.