Christmas is so associated with the 25th of December that it may appear strange that it could ever have been otherwise. The Church in early times was by no means unanimous as to its proper date in the calendar; whether it should come on the 6th of January, the 25th of March or the 25th of December. According to Clement of Alexandria, there was in the second century considerable speculation respecting the date of Christ's birth. Some authorities placed it in the twenty-eighth year of Augustus on the 20th of May, others a month earlier, while Clement himself believed it to have occurred on the 3rd of November in the year 3 B.C. The first certain mention of the 25th of December is made by a Latin chronographer of A.D. 354, who says that Christ was born on the 25th December in the year A.D. 1, on a Friday, on the fifteenth day of the new moon. December 25th, however, in the year A.D. 1 was a Sunday. In the early Church Christmas was not kept as a feast day, as in later times with great festivity and many dishes. The favourite dish used to be a boar's head, but this was supplanted after the middle of the sixteenth century by the turkey.
The Irish Times, December 27th, 1930