As recorded in the bible Jesus Christ was not born on in December 25th(Christmas day) because late December is a cold and rainy season in Judea (which is close to Bethlehem) which would make shepherds not to keep their fragile flocks out in open field.
From the book of Luke(Luke 2:1-3) we know that Jesus Christ was born at time of a census ordered by the roman emperor. The Romans had an organized system that would surely make them not to have a census in a very wet and cold period where snow even falls occasionally.
Jesus Christ our lord did warn us not to adhere to false doctrines so when we organize non-biblical celebration in the name of God and Jesus Christ we're committing a sin in the sight of God. We were told from the book of Deuteronomy (Deuteronomy 12:27-33),that whatever God commands us, we should be careful to observe it and we shall not add or remove from it. Sometimes the society we live in and the churches make us to do things we aren't suppose to do but as Christians we should always give ourselves to diligent study if the bible to know the truth.
If as a christian you are still not convinced do your own in depth research and pray for understanding but take this write-up as food for thought. Member because the multitude do something does not mean it's the right thing