"December 25th began to be celebrated as Christmas, the birthday of Jesus in 354 AD as ordered by Bishop Liberius of Rome." (The World Book Encyclopedia, vol C, # 3, page 416). The Catholic church was not fully developed at that time-the first pope came in 606 AD; apostasy was moving in that direction.
Why did Liberius choose December 25 to celebrate the birth of Jesus? In 312 AD, Constantine had a "vision" at Melvian Bridge. In 313 Ad, Constantine made "Christianity" the state religion of Rome. Masses of pagans like Constantine were converted to "Christianity". They had celebrated the Mithraic Feast of the Sun God at that time of year. As days got shorter, they though their god was losing his strength. Gradually, the days got longer. This pagan festival celebrated the triumph of light over darkness. When they learned of Christ, he became their "new light" so Liberius set December 25th celebrate the birth of Jesus in an effort to turn away attention from these pagan feasts.
Conclusion: December 25 was set by the bishop of the Roman Catholic Church in competition to pagan practices and is not a part of the Christian's religion in origin. The name "Christmas", is from the old English "Christes Masse" meaning "mass of Christ". The apostate church has held a midnight mass on Christmas eve since the 6th century. "Christ" was not used popularly until the 11th century. "Christmas is Roman, Europe speaks of "Christ's birthday" and Scandinavia uses the pagan "Yule Day". NOTE: Christmas, beyond question is America's biggest annual festival. It is a worldy religious, commercial and secular tradition. It is not a part of the worship or practice of the first century church. In fact, the Holy Spirit warned the saints in Galatia against making "holidays" a part of their service to Christ (Gal. 4:9-11). Such have no place in the worship or other activities of the church today. Congregations that have their "Christmas pageants or dramas" are adding to the worship and/or work of the church and are bringing the anathema of Revelation 22:18 upon themselves.