In March 1924, the Synod of Bishops of the Church of Greece voted to accept the Julian Calendar. Since not all the Orthodox accepted the change, different autocephalous churches, and even some faithful within the same church, remained split between two different calendars. Even though all churches celebrate Christ's Resurrection, or Easter, on the same date, all the other non-movable feasts are now celebrated 13 days apart. This includes Christmas.
We won't go into the reasons for this serious change, but let's just say that a rapprochement with the West, especially the Roman Catholic and the Anglican church was the main reason for this breach of centuries-long tradition. Twentieth century witnessed a serious, and perhaps irreversible meddling of politics into spiritual life.
Although I don't believe calendar is crucial for one's salvation, there are many good reasons for sticking to the old, Julian Calendar. One of them is not celebrating Christ's birth on Christmas.
Even though it bears our Saviour's name, Christmas is everything but a celebration of God's Incarnation, the event that altered the essence and meaning of our existence. The gathering of a family, presents, the festive and serene moments on Christmas Eve and Christmas Day are hard to criticise. They foster love, the feeling of belonging to a community and the exercise of selflessness. There is one other aspect of Christmas, however, the most obvious one, which is not in any way connected to the celebration of our faith: the commercial aspect of Christmas.
The imperative to buy presents, to spend money, to find the best quality for best prices, the crowds in shopping malls and the race for procuring material things, albeit for others, stands at the opposite end of the commemoration of one of the two most significant events of our faith. The consumer frenzy surrounding the biggest holiday in the West is certainly not something Christ would commend.
The Old Calendarists, therefore, can celebrate Christmas as a family holiday, as a nice occasion to demonstrate care and appreciation for the loved ones with a Christmas tree, and enjoy the heartfelt, cozy moments this holiday brings. But the peaceful and solemn celebration of the arrival of God's son to our fallen world should remain 13 days apart, past the recovering aftermath of the shopping craze at the end of the year.
And that's why this sacred celebration does not and should not share its name with the preceding commercial holiday. Appropriately, it is called Nativity.