Look friend, everything I stated was true. If you want to qualify and develop it further, that's fine. But you don't have to be a nimrod about it.
As of 2012, there is a difference of 13 days between the modern Gregorian calendar and the older Julian calendar. Those who continue to use the Julian calendar or its equivalents thus celebrate December 25 and January 6 on what for the majority of the world is now January 7 and January 19 (due to date creep associated with the difference between the Gregorian and Julian calendars).
For this reason, Ethiopia, Russia, Ukraine, Serbia, the Republic of Macedonia, and the Republic of Moldova celebrate Christmas on what in the Gregorian calendar is January 7; all the Greek Orthodox Churches celebrate Christmas on December 25.
Now, the Gregorian calendar was introduced by Pope Gregory XIII on 24 February 1582 by Papal Bull. So before that the Julian calendar was used.
All Christian churches celebrated Christ's birth on January 6 until the fourth century. According to historical sources (including the Roman Catholic Church), the date was changed from January 6 to December 25 in order to override a pagan feast dedicated to the birth of the Sun (exactly as I stated) which was celebrated on December 25. Roman Christians were seeking to udermine and subdue this pagan practice and they were successful in that endeavor.
Happy?