The entire reason Christmas was celebrated on December 25th was to shift it and allow it to coincide with the Winter Solstice festival. This had the double advantage of appealing to pagans by integrating one of their most important religion, as well as presenting a clear and effective link. The Sun was the champion of the gods in most mythologies, and the safekeeper of the world. Therefore, it was logical to celebrate Jesus' birth around then. Also, I believe historians have records of the months in which the first Census took place (which was the reason why and a nice landmark for Jesus' birthdate). I don't remember the exact dates, but it was concluded to be in the summer. Also, Gauntlet, about the sheep habits being different in the north and in the Middle East: Middle Eastern nights, especially in December, can be extremely cold (trust me). Sheep would be just as inclined to by in a shelter during that time (sheperds were watching their flocks by night which, had Jesus been born in December, would have been extremely cold) as sheep in Northern Europe.
The 25th was a day when people decided christ was born, his actualy date of birth is unknown.
Heaven's gonna burn your eyes
16th April 2005
In 11th century England, this was a big issue. The old Christian calender's New Year started on 25th December, and the Roman calendar started on the 1st of January. It turned into a three way debate, when some people though that the new year could start on Lady Day, 25th March (exactly 9 months before Christmas).
Anyway, the Roman calender won New Year's.