"And there were in the same country shepherds abiding in the field, keeping ||watch over their flock by night."
Now, we know that shepherds would not be tending their flocks in December. December 25 was picked by the Romans to match up with pagan festivals in order to Christianize Rome.
When pagans where converted they did not leave behind all their traditions. Many were blended into Christianity especially many of the ways we celebrate holidays like Christmas and Easter. There are no accounts of how the earliest Christians celebrated Christmas but trees, stockings and mistletoe where most certainly not a part of it.
The idea of Christmas originally came from pagans. They would celebrate their holiday, Saturnalia, from Dec 17-25th. After a few years many pagans converted into Christians and continued to celebrate during that time of year, but slightly changed the name of the holiday and how they went about celebrating it.
Christmas is a combination of several different traditions most of which pre-date Christianity. The bible does not provide a date for Jesus' birth, and it is not mentioned in the bible as a celebration or festival. The Romans originally had a pagan festival around the winter solstice. The Christmas tree came from the Viking Yule Log Ceremony. Christmas was outlawed by the Puritans who recognized it as a pagan holiday that had been adapted.
Christmas is celebrated on December 25 which is the day that is claimed for Jesus's birthday. The Bible also states as the first commandment "Thou Shalt Not Have Any Gods before me." Saying that Christmas is from another religion is breaking the first commandment. This is putting another religion before Christianity.