No one is really sure why Christmas is on December 25th every year or why the Christian Christmas got all tangled up with all of the pagan celebrations. The Bible is actually very vague on the life of Jesus and focuses more on his teachings than him as a person. So we are not really given an exact date of his birth anywhere in the Bible. So how did December 25th get choosen? In the Christian religion the date of March 25 is very important. Many Christians believe that the angle appeared to Mary on March 25th to tell her that she was pregnant with Jesus. A long time ago the Christian religion believed that Jesus was crucified on March 25th and they also believed that March 25th coincided with the creation of Adam. So back in the very early days some Christian authorities simply went 9 months from March 25th and came up with December 25th as the Christian Christmas. Many cultures also celebrate the Epiphany on January 6th as the day the wise men arrived to visit Jesus. January 6th is 12 days from December 25th so that is where the Twelve Days Of Christmas comes from. If you look at the history of the Christian Christmas you start to realize that a lot of it is guessing and coincidence rather than any hard facts or proof of any dates. But when you are dealing with religion you deal with faith and that is what carries much of this.
For centuries after the death of Jesus his birthday was not celebrated. Early Christians were more interested in celebrating what they felt was the day of the baptism of Jesus which they celebrated during the Epiphany of January 6th. As the Middle Ages came around the festival of Christmas was starting to dominate the calendar and soon the time months before, and after, the Christian Christmas were dotted with holidays based on Christmas day. As time went by Christians celebrating Christmas had turned the holiday into a drunken mess and the Protestants saw to outlaw it due to anti-Catholic sentiments. For a short time in the 1600’s Christmas was banned but a siege of Canterbury by pro-Christmas rebels caused it to be reinstated. From there the celebration changed and grew and when it reached the new world of America other cultures started mixing in their Christmas traditions that they had gained from pagan festivals and soon the Christian Christmas was starting to get swallowed up once again by a drunken mess.