Calculating Christmas (an article I reposted from Touchstone Magazine, Tighe, 2003).
This topic came up again in a family discussion last night (Christmas Night) after we had Christmas dinner (which, due to lack of planning on our part was at Denny's - hey, "They're always open!"). The discussion was back at my place as we sat around the Christmas tree enjoying some egg nog and other festive beverages. Someone mentioned the pagan origins of the date of Christmas and when I mentioned that in reality the date had nothing to do with pagan origins - rather it was based upon the date believed to be the Conception of Jesus on March 25th which brought us to December 25th (nine months later).
Dates brought up were for Saternalia (which always ended BY December 23rd - One must ask too, why would the Catholic hierarchy have picked a date TWO DAYS AFTER Saternalia if they wanted to "replace" that celebration with the Christ Mass?) and Sol Invictus, which was celebrated on December 25th - but not until late in the 3rd century - and Catholics had already been celebrating Christmas on December 25th by that time! In fact the Roman Emperor, Aurelius, who instituted Sol Invictus, is said to have done so to counter the growing popularity of the Catholic holiday of the Christ Mass (Christmas).
Also, at least as early as the second century, the Feast of the Conception of John the Baptist was celebrated on September 9th. Scripture states that the Annunciation took place in the sixth month of Elizabeth's (John the Baptist's mother) pregnancy. Go six months out from September and you have March.
Now, considering that ancient belief was that one's death date was the same as their conception date, in Eastern Christianity they went with April 6th as this date for Good Friday while the West settled on March 25th. One problem we'd have with the Eastern date is "instead of working off of 14 Nisan from the Hebrew calendar they used the 14th of the first spring month (Artemisios) in their Greek calendar–April 6 to us. And April 6 is, of course, exactly 9 months before the eastern date for the birth of Jesus, January 6." (qtd. from Barney. 2006). The West used 14 Nisan and came up with March 25th. This is also why Eastern Orthodoxy and Catholic/Western Easter usually falls upon different days.
For more information and discussion, I recommend the following (short) videos too:
Fr. Mitch Pacwa and Dr. Scott Hahn correct a young priest or seminarian:
And from Defeat Modernism (defeatmodernism.com) the commentary goes into more details:
Barney, 2006 - April 6th and the Conception of Jesus - https://bycommonconsent.com/2006/12/03/april-sixth-and-the-conception-of-jesus/
Defeating Modernism - video - https://www.youtube.com/watch?v=ZzjReUVjmcA
EWTN Live - video - https://www.youtube.com/watch?v=cD79TZCemJ0
Tighe, William J. - Touchstone Magazine - Calculating Christmas - http://www.touchstonemag.com/archives/article.php?id=16-10-012-v