Any historian will tell you that the Roman Empire normally collected taxes in the autumn — after the harvest — for the very pragmatic reason that this was when people had money to pay. In fact, there are records that indicate the most famous tax decree in history — the one that forced Joseph and a very pregnant Mary to journey to Bethlehem — actually happened in late September. Which means Jesus was almost certainly born a Libra — if you believe in that sort of thing. So why do we celebrate Christmas, the birth of Christ, on December 25th?
It’s not rocket surgery, folks; it’s marketing.
The early Christians weren’t idiots (despite what contemporary anti-Christian loudmouths might tell us.) They understood that when you’re the new kid in town and your doctrine is heavy on the “thou shalt nots” you need a few bells and whistles to pull people into the pews. This was especially true, back in the day when there were enough gods and goddesses wandering around Europe to fill Wembley Stadium, and at least half of them were hooked into fertility. Let’s face it: kneeling on cold stone, repenting your sins, doesn’t look all that attractive when there’s a good-old-fashioned fertility ritual (“orgy” is such a hard word) goin’ on down the block. So one of the first things the new-fangled Christian Church did was hitch its festivals to all the pagan holidays that were being celebrated across the continent. The idea was to score some pretty radical religious change by easing the locals into the notion. For example, Easter, the highest Christian holiday is connected to the Norse and Anglo Saxon goddess of spring, Eastre (Eostre? Aster? depending on your translation) whose symbol is the rabbit. Thus, it was no great leap for early Christians to look at the Roman Saturnalia Festival (December 17th on your Julian calendar) and say, “Wait a minute!” especially since Saturnalia celebrated the Winter Solstice with banquets, dancing and gift-giving.
The truth is we celebrate Christmas, the birth of Christ, on December 25th, because our ancestors saw a kickass marketing strategy and used it. But who cares? Those of us who celebrate Christmas do it because we like it. It’s fun. And the bottom line is it doesn’t matter if we haven’t got a birth certificate.