Loads of adopted children end up celebrating their birthdays on the date that is the best estimate of the actual date. But in fact, it does not really matter because what is being celebrated is the fact that that person emerged from the womb to begin life on his own in this scary wonderful world.
There is scripture that tells us of the glories of God. I leap for joy at every single fact I know about Jesus from the gospels. And we are commanded to honor God and His word - so in fact to set a side a special day for the world to dwell on the gospel story of His birth is extremely biblical and it is absurd that anyone claiming to love the gospels is upset that the there is unity in celebrating His birth each year.
Objections to the worldwide gospel-fest known as Christmas are based on pride, and nothing else.
There is no scripture stating you should have responded to that post, you filthy heathen.