"Certain Latins, as
early as [A.D.] 354, may have transferred the birth day
from January 6th to December 25, which was then a Mithraic
feast . . . or birthday of the unconquered sun . . . The Syrians and
Armenians accused the Romans of sun worship and idolatry."
-
Encyclopedia Britannica, (1946 ed)
"the date of
Christ’s birth did not become an issue until sometime in
the fourth century. At that time the dispute centered
primarily over two dates for Christ’s birth: December 25 promoted
by the Church of Rome and January 6, known as the Epiphany,
observed by the Eastern churches. “Both these days,” as
Oscar Cullmann points out, “were pagan festivals whose meaning
provided a starting point for the specifically Christian
conception of Christmas."
- The Meaning, Celebration and Date of
Christmas, by Dr. Samuele Bacchiocchi, p.14
(quoting from The Early Church, by Oscar Cullmann, 1956, p.35.)