November 14th starts the 40-day Christmas Fasting, introduced by the Church later than the Holy Fasting for Easter. In 1166 the Patriarch of Constantinople, Luke Chrysoberges, defined the Christmas Fasting Days to be exactly 40.

The celebrations of the Holy Nativity feast became popular around the year of 350 AD in the western Europe, while in Eastern Europe they were first introduced by St Gregorii Bogoslov (i.e. St Gregory the Theologian) around 375 – 380 AD. Holy Nativity was celebrated on a number of different days throughout Christian world – Dec.25 in the western parts, January 4 in Antiochia, April 18 or 19 or May 29 in Alexandria, and January 6 or 10 in Asia Minor…. It was not until the end of the 4th c. AD that these celebrations were appointed on one day for all the churches (except the Armenian) - i.e. the date of Dec.25th.