The Origin of Christmas

excerpts taken from christmas.com

Christmas is the celebration of the birth of Jesus Christ. Whether he was born on December 25th, no one can say. Most sources cite the birth occurred on the 25th of the month, but which month is uncertain and at one time or another it has been assigned to every month. As early as before 220AD it has been celebrated on Dec. 25th. During the third century it was a common belief that Christ was born during the winter solstice based on interpretation of prophetic scriptures. One third century set of writings, The Apostolic Constitutions, indicate that the birth of Christ was celebrated on the 25th day of the ninth month (which would now be December). The Roman Church finally fixed December 25th as the birthday of Jesus Christ. Christ Mass, later called Christmas, was first celebrated in the year 354AD, December 25th, according to several sources.

References for the first Christmas appear in the Books of Luke and Matthew in the King James version of the Bible.