There is a new book out debunking many of the pet theories of the various Armstrongite splinter groups that they use to defend their stance on not keeping Christmas.
The book is entitled: The Eternal City: Rome & and Origins of Catholic Christianity. by Taylor Marshall
Sadly, because this book is written from a Catholic point of view those steeped in the cult of Armstrongism will NEVER entertain a divergent view than what they were brought up with. Never mind the fact that Marshall has more theological training than ANY of the COG leaders do.
Some of the points he discusses on his blog are:
Objection 1: December 25 was chosen in order to replace the pagan Roman festival of Saturnalia. Saturnalia was a popular winter festival and so the Catholic Church prudently substituted Christmas in its place.
Objection 2: December 25 was chosen to replace the pagan Roman holiday Natalis Solis Invicti which means “Birthday of the Unconquered Sun.”
Objection 3: Christ could not have been born in December since Saint Luke describes shepherds herding in the neighboring fields of Bethlehem. Shepherds do not herd during the winter. Thus, Christ was not born in winter.