Christmas is a day celebrating the birth of Jesus Christ, who many Christians believe is the son of God.

While many celebrate Christmas on December 25, some Orthodox Christians mark it on January 7.

Birth of Jesus

Not an exact date. The exact date of Jesus' birth has not been established in any secular text. With a lack of historical evidence, the date has been estimated by analysing the historical events mentioned in the gospels of Luke and Matthew and the ministry of Jesus.

The January 7 date is based on the Julian calendar for religious celebrations, which existed before the Gregorian one.

Old Christmas day. Christmas on January 7 is also known as Old Christmas Day. Days were removed to make up for the difference with the Julian calendar when England switched to the Gregorian one in 1752.

Many people did not accept the change and preferred to use the Julian calendar.

More than a third of Orthodox Christians. In Russia, home to 39 percent of the world's Orthodox Christians, people celebrate Christmas Eve on January 6 with services, and on January 7 they mark the birth of Jesus.

The Armenian Apostolic Church celebrates Christmas on January 6, along with the Epiphany (the revelation that Jesus was God's son).

Sunday was the earliest Christian celebration. In the second century, the Resurrection became a separate feast and the Epiphany began to be celebrated in eastern churches on January 6.

Where was Jesus born?

Bethlehem, Palestine. The gospels of Luke and Matthew state that Jesus was born in the Palestinian town of Bethlehem in the days of King Herod.

Mary lived in Nazareth. The gospels explain that Mary lived in Nazareth before the birth of Jesus and at the time of the Annunciation. Jesus was born in Bethlehem, but the family later settled in Nazareth.

The Quran also places his birth in Bethlehem.

Orthodox celebrations in photos