In my faith, we believe the date of Christ's birth to be April 6th. That said, as a church we celebrate Christmas on Dec. 25th with the rest of Christianity, and not on April 6th. Why? Because the date itself is not so important, as fistful was saying. What is important is Christ's birth and that we remember it and its significance.
Maybe it's more important to celebrate the birth of the Messiah at a time when the days begin to lengthen, symbolizing renewed hope and deliverance from darkness.
That's not a perspective I've thought of before, but I quite like it.