While most Christians celebrate Christmas on 25 December every year, for Coptic Orthodox Christians - mainly in Egypt and Russia - it comes later.
The 7 January rituals include praying and fasting for a certain period of time.
"We fast for 43 days but it's light fasting where we eat vegan food and are allowed fish too," Nadine El Erian, one Orthodox Coptic Christian said.
"On the night of the 7th of January we go to church for the mass and then we break the fast and begin celebrations."
Orthodox Christians light candles during a Christmas liturgy at the Kazan Cathedral. Source: Getty Images
Australian communities celebrates
Hundreds of Australian Coptic Christians in Sydney turned out on Sunday night to mark their Christmas Eve. A mass was held at St Marks Coptic church.
Head of the Public Affairs Council for the Coptic Orthodox Diocese of Sydney, John Nour, said it is a special celebration to mark the birth of Jesus.
“We have over 100,000 Coptic people living in Australia, and during that time we celebrate the birth of Christ,” Mr Nour told SBS News.
“It’s a quite long mass and normally finishes at midnight, people and their families then get together and meet for dinner.
“Most of us will have Monday off so we celebrate the 7th of January."
Inside St Mark's Coptic Orthodox Church in Sydney Source: SBS
"Eating a lot of meat, drinking a lot and families getting together," Mr Nour said.
"It's the happiest time of the year and it's very important for us that the kids get engaged in the church and the mass.
“Our kids are the future of the church.”
Celebrating around the world
On Sunday, Serbian Orthodox Christians gathered at Saint Sava Church in Belgrade to celebrate Christmas Eve by burning oak branches. The young oak tree symbolises Christ and his entry into the world.
Serbian Patriarch Irinej, the spiritual leader of Eastern Orthodox Serbs, followed the centuries-old tradition of burning the oak branches and offered holiday greetings.
Source: AP
Protests in Jerusalem
Hundreds of Orthodox Christians began marking Christmas in Bethlehem Sunday, as protesters demonstrated against the sale of church land to Israelis.
Greek Orthodox Patriarch Theophilos III arrived at the Church of the Nativity, built on the traditionally recognised site of Jesus's birth, as a large deployment of Palestinian police stood guard.
Several dozen demonstrators shouted "traitor" and "spy" as they protested against the Greek Orthodox church's sale of property in east Jerusalem to groups aiding Jewish settlement.
Israeli purchases of church land and property in east Jerusalem has caused anger among Palestinians - including Orthodox Christians - who see the territory as the capital of their promised state. A similar protest took place last year.
The Bethlehem municipality in the West Bank had decided not to welcome Theophilos officially, councillor Anton Salman told AFP. He called on the Greek Orthodox leader "to remain faithful to the cause of the Palestinian people".
The church of the nativity ahead of the arrival of Jerusalem's Greek Orthodox patriarch Theophilos III in the West Bank town of Bethlehem on January 6, 2019. Source: AFP
Most Eastern Orthodox Christians celebrate Christmas on 7 January, while those in the West observe it on 25 December because of differences between the Julian and Gregorian calendars.
Earlier on Sunday the traditional parade of boy and girl scout marching bands in Bethlehem went ahead in a biting cold wind.
"We came to visit Manger Square to celebrate Christmas," said Lissa Bsharat, who had arrived from Nazareth in northern Israel with her son and husband.
"The atmosphere is very beautiful."
