How many Christians know that......?

Your holidays are nothing more than mere Pagan traditions? Like for an example Christmas. During the later periods of Roman history, sun worship gained in importance and ultimately led to what has been called a 'solar monotheism.' Nearly all the gods of the period were possessed of Solar qualities, and both Christ and Mithra acquired the traits of solar deities. The feast of Sol and Victus (open unconquered Sun) on December 25th was celebrated with great joy, and eventually this date was taken over by the Christians as Christmas, the birthday of Christ. That being said Christians were trying to blend in Pagan holidays to do nothing more than convert Pagans to their beliefs. No were in the bible does it ever say to celebrate Christs Birthday. The Messiah was not born December 25th. He did not ask us to celebrate his birthday. He did not say to set up a tree in our house and decorate it and our houses with anything. Santa Claus does not exist. He doesn't have reindeer that fly and he isn't going to come on December 25th and leave any gifts. So why do so many people heavly tie holidays like this and other ( Easter) as being Christian when it's not?