. . since Sol Invictus, birthday of the Sun, is solidly on the 25th, and is the holiday appropriated by the Christians for the birth of Jesus.

All details of the story point to birth in the spring. Tax time was in the spring in the Roman Empire as it is today - and shepherds would not have been out in the field in December.

They couldn't place Jesus birth in the spring because they needed the Pagan rebirth holiday for the crucifixion and resurrection.

These assignments were purely to commercialize the product - and to think today Christians complain about commercialization.