Why are some Middle Eastern Christians celebrating Christmas in January?

Christians in the Middle East celebrated one of the most important dates in their calendar on Wednesday - Christmas

Yet the celebrations come 13 days after Christmas celebrations across much of the world.

So why are some Arab Christians celebrating today, and which Christian denominations are they? The New Arab takes a look.

The Julian Calendar

The reason why some Christians celebrate on 7 January instead of 25 December is because of their use of the Julian Calendar, rather than the Gregorian Calendar, which is commonly used across the world today.

Although older, being introduced by Julius Caesar in 46 BC, the Julian Calendar is less accurate from an astronomical point of view than the Gregorian calendar, losing a day every 128 years instead of the one day every 3,236 years of its counterpart.

Because of the accuracy issue, a split emerged between the Catholic Church and its eastern counterparts, with Pope Gregory XIII mandating the Gregorian Calendar's adoption in 1582.

Therefore, although Christmas in the Julian Calendar is still dated to 25 December, under the Gregorian Calendar, that date now falls on 7 January.

Which denominations celebrate?

With Christianity emerging originally from the Middle East, there are several Christian denominations in the region that continue to celebrate using the Julian Calendar.

This includes Egypt's Coptic Orthodox Church. Coptic Christians form roughly 10 per cent of Egypt's population.

The Church is one of the oldest in Christianity, tracing its roots back to St Mark, who is traditionally known as the author of one of the Gospels.

Many Greek Orthodox communities in the Middle East, including those in Palestine, Syria and Lebanon, also celebrate on 7 January, with the Church of St Prophyrius in Gaza holding mass.

The Armenian Apostolic Church, whose communities exist in Palestine, Syria and Lebanon, also celebrates on Wednesday, as do the region's Syriac Orthodox Churches, with Syriac Press reporting that Syria's Syriac Patriarch Mor Ignatius Aphrem II met with his Armenian counterpartArchbishop Armash Nalbandian for the celebrations.

Other notable Orthodox churches across the world that celebrate Christmas on the 7 January include the Russian Orthodox Church, Serbian and Georgian Orthodox Churches, and the Ethiopian and Eritrean Orthodox Tewahedo Churches.