Orthodox Christians mark Christmas on Jan. 7, reflecting calendar differences

Millions of Orthodox Christians around the world marked Christmas on Wednesday, Jan. 7, nearly two weeks after much of the world marked the holiday, according to the Associated Press.

The different dates are tied to which calendar system a church follows. Certain Eastern Orthodox churches, including those in Russian traditions, observe Christmas according to the Julian calendar, which runs 13 days later than the Gregorian calendar used by Catholic and Protestant churches and by much of the secular world for everyday life.

Other Orthodox and related traditions followed Wednesday as well. The Ethiopian Orthodox Church and some other Oriental Orthodox churches—distinct from Eastern Orthodox but sharing many traditions—also celebrated Christmas on Wednesday. By contrast, other Eastern Orthodox, including those in the Greek tradition, celebrated Christmas on the same Dec. 25 date as Catholic and Protestant churches.

At the center of the disagreement is how the fixed date is mapped to the calendar. Most Orthodox agree that Dec. 25 is the date of Christmas, also called the Feast of the Nativity, but the question is whether Dec. 25 falls on Dec. 25 or on Jan. 7, the AP said.

That issue traces back to how religious feasts were set historically in the Roman Empire. The ancient church in that empire tied religious feasts to the Julian calendar, but over time the Julian calendar increasingly drifted out of alignment with the solar year.

In the 16th century, Pope Gregory XIII approved a revised, more astronomically precise calendar named for him. The change shifted the calendar several days forward to account for lost time and included a more precise calculation of leap years. Protestant churches later adopted the revised calendar following the Catholic lead, and secular governments also followed.

Eastern Orthodox churches largely did not adopt that change. The AP said that most Eastern Orthodox kept to the old calendar until 1923, when an inter-Orthodox gathering adopted a revised Julian calendar that essentially mirrors the Gregorian calendar. The Greek Orthodox tradition has mostly adopted that revised calendar, and other traditions such as Romanian and Bulgarian have done so as well, though not all churches in Greece have made the shift.

The Russian Orthodox Church, however, has stayed on the old calendar, observing Christmas on Jan. 7 on the new calendar, and other Orthodox groups including those in Serbian and Georgian traditions have continued the Jan. 7 observance, the AP reported. In Ukraine, some Orthodox have begun to observe Christmas on Dec. 25 while others have retained the Jan. 7 observance. The AP also noted that the Armenian Orthodox tradition observes Christmas on Jan. 6.

Orthodox Christmas traditions also vary across locations. In the United States, churches in the Greek and Antiochian traditions observed Christmas on Dec. 25, while some churches in the Slavic tradition—including Serbian and smaller Russian churches—observe it on Jan. 7, according to the AP.

Traditions for the holiday include worship services that often begin on the evening before Christmas. The AP said that in Serbian Orthodox churches, worship often starts with a short outdoor ceremony involving the burning of an oak branch or young oak tree, accompanied by a proclamation of the birth of Christ.