I found this interesting article. www.gotquestions.org
Question: "Was Jesus born on December 25? Is December 25 Jesus' birthday?"
Answer: Speculation as to the time of Jesus’ birth dates back to the 3rd century, when Hyppolytus (ca. 170-236) claimed that Jesus was born on December 25. The earliest mention of some sort of observance on that date is in the Philoclian Calendar, representing Roman practice, of the year 336. Later, John Chrysostom favored the same date of birth. Cyril of Jerusalem (348-386) had access to the original Roman birth census, which also documented that Jesus was born on the 25th of December. The date eventually became the officially recognized date for Christmas in part because it coincided with the pagan festivals celebrating Saturnalia and the winter solstice. The church thereby offered people a Christian alternative to the pagan festivities and eventually reinterpreted many of their symbols and actions in ways acceptable to Christian faith and practice.
December 25 has become more and more acceptable as the birth date of Jesus. However, some argue that the birth occurred in some other season, such as in the fall. Followers of this theory claim that the Judean winters were too cold for shepherds to be watching their flocks by night. History proves otherwise, however, and we have historical evidence that unblemished lambs for the Temple sacrifice were in fact kept in the fields near Bethlehem during the winter months. With that said, it is impossible to prove whether or not Jesus was born on December 25. And, ultimately, it does not matter.
The truth is we simply don’t know the exact date of our Savior’s birth. In fact, we don’t even know for sure the year in which He was born. Scholars believe it was somewhere between 6 B.C. and 4 B.C. One thing is clear: if God felt it was important for us to know the exact date of the Savior’s birth, He certainly would have told us in His Word. The Gospel of Luke gives very specific details about the event, even down to what the baby was wearing – “swaddling clothes”—and where he slept—“in a manger” (Luke 2:12). These details are important because they speak of His nature and character, meek and lowly. But the exact date of His birth has no significance whatsoever, which may be why God chose not to mention it.
The fact is that He was born, that He came into the world to atone for our sins, that He was resurrected to eternal life, and that He’s alive today. This is what we should celebrate, as we are told in the Old Testament in such passages as Zechariah 2:10: “'Shout and be glad, O Daughter of Zion. For I am coming, and I will live among you,' declares the LORD.” Further, the angel that announced the birth to the shepherds brought “good news of great joy that will be for all the people” (Luke 2:10). Surely here is the cause for celebration every day, not just once a year.
Read more: http://www.gotquestions.org/December-25.html#ixzz3LjdFGDQF