Why about 250m Christians celebrate Christmas on January 7

Millions of Christians around the world are marking Christmas on January 7, a tradition observed by an estimated 250 million believers, mainly within Orthodox and Coptic Christian communities.

The difference in dates is not due to a belief that Jesus was born on another day, but because these churches follow a different calendar system.

The split in Christmas dates dates back to 1582 when Pope Gregory XIII introduced the Gregorian calendar, which better aligned with the solar year than the older Julian calendar established by Julius Caesar.

While much of the world adopted the Gregorian calendar, many Orthodox and Eastern Christian churches continued to use the Julian calendar for religious observances.

Al Jazeera noted that today, the Julian calendar runs 13 days behind the Gregorian calendar, so December 25 on the Julian calendar falls on January 7 in the modern system.

Churches that follow this tradition include the Russian Orthodox Church, the Serbian and Georgian Orthodox Churches, the Coptic Orthodox Church of Egypt, and the Ethiopian and Eritrean Orthodox Tewahedo Churches.

In contrast, around two billion Christians worldwide, including most Catholics, Protestants, and some Orthodox churches that follow the Gregorian calendar, celebrate Christmas on December 25.

In some countries with Orthodox Christian majorities, both dates are recognized as public holidays.

In places like Ukraine, the official public holiday has been moved to December 25, although many still observe the January 7 celebration.

Over time, the calendar difference will gradually widen, and if the Julian calendar continues to be used, Orthodox Christmas could shift to January 8 by the year 2101.