The congregation at Narrabundah's St John the Baptist Church will be gathering Sunday morning for its traditional Christmas liturgy, says parish priest Father Alexander Morozow.

''In the Orthodox Church, Christmas is - as everywhere - on the 25th,'' he said.

''But because we use the Julian calendar, which is now 13 days behind the modern-day calendar, our 25th of December now happens to fall on the 7th of January.''

Father Alexander said there were about 30 people in the church's core congregation, a count which fluctuated with the capital's changing population, who celebrated Christmas Eve on Saturday.

''Some people hold out for all the celebrations this weekend,'' he said. ''Others perhaps have gift giving on the 25th and then have a church Christmas later.''

While children may receive presents from Grandfather Frost instead of Santa, Father Alexander said there was one thing both the ''Western'' and Orthodox congregations agreed on - overindulging in Christmas dinner.

But for those in the Russian Orthodox Church, it's the only excess of the season.

''There's an Advent, a six-week period of Lent where those who are devout will abstain from meat and other animal foods for the six weeks leading up to Christmas,'' he said. ''Lent finishes on Christmas Day, so after the liturgy people go home and tuck in.''

This year's Christmas celebrations also mark the culmination of almost 30 years of iconography work, with Father Alexander unveiling 12 freshly painted medallions of saints around the walls of the ornate building.

''The saints you find in these medallions aren't the ones you'd expect to find in a Russian Orthodox Church,'' he said.

''They're ancient Western saints that in fact are also saints in the Orthodox Church.''

Father Alexander said the mix of saints was a deliberate choice, to reflect on the multicultural nature of Canberra, and work would be continued over the next year on the lone blank wall left in the church.