They celebrate Christmas on a day in January, not in December.
Nativity of the Lord (Christmas)
(7th of January)
Christmas is a Christian holiday that commemorates the birth of Jesus, who Christians believe is the son of God. The nativity of Jesus is considered to be one of the most important dates for Christians. A special Mass or church service is held in various churches throughout the world. Christians from different cultures celebrate Christmas Day in different ways.
In the Eastern Orthodox tradition, it is common to celebrate the event on Christmas Eve. Catholic and Protestant traditions typically set the date of Jesus according to the Gregorian calendar (25th of December) while Eastern Catholic Churches and Eastern Orthodox Churches calculate the date according to the Julian calendar (7th of January). Eastern Catholic and Orthodox calculate the date according to the Julian calendar (7th of January). The event is one of twelve feast days.
I’m Gregorian................