In the December 1982 issue of The Orthodox Church Bishop BASIL, then the Bishop of San Francisco and Western US wrote an article on the question of the calendar.
Since many people ask whether the calendar, which was adopted by the OCA in Sepgember 1982, is not really a Roman Catholic Gregorian calendar, it is important to restate again that it is a genuine Orthodox calendar, revised by the Orthodox Church herself.
It was actually the First Ecumenical Council which reformed the calendar by moving the date of the Spring equinox back four days -- from the 24th to the 21st of March (because over four centuries, four days were gained in the calendar, one each century). The Council fixed this astronomical date connected with Easter, in the movable calendar. In other words, the Council affirmed two points: an unchanging fixed date of the Spring equinox which determines the date of Pascha, and a flexible calendar which does not corresond to astronomically fixed conditions. Thus, the date of Pascha is closely connected with the calendar and its introduction into the generally accepted calendar signifies the beginning of a new general "revised" calendar which is no longer pagan, but Christian.
Thus the First Ecumenical Council actually led the Church to a decision to keep a fixed date for the Spring euinox -- 21 March -- and to change the calendar, revising it according to the scientific data and historical development as necessary for the observance of Pascha. In other words, it is not to be thought that the calendar is as fixed as the dates of the Spring equinox, and to remember that the calendar is not a dogma.
In 1923 an Orthodox Commission, meeting in Constantinople decided to reform the calendar--not blindly following the Roman Catholic Gregorian calendar, but in accordance with the decision of the First Ecumenical Council.
Indeed, time will come when the date of the Spring euinox will again have to be fixed anew. Under the present calculation the Spring equinox will remain on March 21 for more than 40,000 years, but after that, a new reform will be needed.
Meanwhile, according to the uncorrected Julian calendar ("old" calendar), the date of the Spring euinox falls on the 8th of March, and is moving back with every new century. Eventually, time may come when the Spring equinox would be in the Fall!
The Orthodox Conference of 1923 made the necessary adjustment, but not in reference ot Pascha. The fixing of the date of Pascha will have to remain unrevised until the complicated issue of its connection with the Jewish Passover can be solved by all the Orthodox Churches together.
The Orthodox Church in America has followed the decision taken by the Orthodox Conference of 1923 with a sincere awareness of her duty, and according to conscience and conviction.
+BASIL Bishop of San Francisco and Western US
His Beatitude and Members of the Holy Synod