There is a passage in the Doctrine and Covenants which has been interpreted as indicating that Jesus was actually born on the equivalent of April 6th. Many Church materials have been published which have accepted that interpretation.
Many modern Christian scholars have found reason to argue for a birth date in fall, perhaps in September, based on apparent references to Jewish festivals.
Why would there be any confusion? Isn't there a record?
As a matter of fact, the best we know at this point is that there was no record, nor was there any observance of his birthday during rhe first two hundred or so years of the primative Church. One could well wonder if Jesus would have preferred to avoid paganisms like celebrating the birth of God.
Somewhere in the second and third centuries, the Roman politicians felt a need to have such celebrations. And apparently there was some sentiment that it would be convenient if the birthday were close to the winter solstice festival of the birth of the sun. A Christian festival of the importance of the birth of the son of God, to replace the pagan festival, was deemed strategic.
They persuaded Churchmen to research the issue, and several were able to come up with a line of logic to place the Conception during spring, which would place the birth near winter solstice. Actual calculations varied a bit. But the convenience was undeniable. Thus, a bit at a time, the Christ Mass celebration of the Savior's birth near the day of the old birth of the sun celebration grew in importance.
So, maybe Christmas isn't really Jesus' birthday.
Does it matter?
Many (maybe most) Mormons who have investigated the question this far feel that it really doesn't matter that much. The celebrations which the Lord commands us to observe regularly to remember our Savior are participation in the Sacrament of the Lord's Supper, in which we renew our covenant of baptism, and our daily prayers.
Any other excuse to remember our Savior does not seem to need critical review. And if we can celebrate with our neighbors and use it as a good reason for talking about treating each other kindly and such, all the better.
So we who think this way celebrate Christmas in various ways. (And generally try to find ways to make it more than just a commercial reason to buy each other gifts.)
