Religious Affairs Office

To understand the difference between the calendars of the Orthodox Church and the Roman Catholic Church, we have to look at the differences between the Julian and the Gregorian calendar. The Julian calendar is the one that was introduced in the year 46 BC by Julius Caesar to all of the Roman Empire, and it is the calendar that was used during the life of Jesus Christ and at the time of the early Church. Over time this calendar developed an error in relation to the astronomical calendar, and for this reason, in the year 1582 Pope Gregory XIII issued a change of calendar, correcting the inconsistency in relation to the astronomical calendar. The two calendars are now 14 days out of synchronisation with each other. This change took time to be recognised by many countries, but eventually, from the beginning of the 20th Century, all the countries in the world had accepted it as the civil calendar.

The first Ecumenical Council, in the year 325 AD, determined the way of choosing the date each year for the celebration of Easter, the Resurrection of Our Lord Jesus Christ. It was set on the first Sunday after the first full moon following the spring equinox (March 21), and it was determined that all of the Christian Churches would celebrate Easter on the same date. It was like this for many years, but after the installation of the Gregorian calendar there began to be differences in the dates of the Easter celebration between the Orthodox Church and the Roman Catholic Church.

The Orthodox Church celebrates moveable feasts, which are all those that depend on the date of Easter, according to the Julian calendar. Therefore, all the Orthodox Churches celebrate Easter on the same date, according to the recommendations of the first Ecumenical Council. This date may or may not coincide with the Roman Catholic Church’s Easter celebration, because there is a difference of 14 days between the Julian and the Gregorian calendar. The Orthodox Easter celebration can coincide with the Roman Catholic Easter, it can be celebrated the following Sunday, or there can be more than a month between them if they have had to wait for a new full moon.

When it comes to fixed feasts, which are all the feasts celebrated on a specific day in the calendar, the Orthodox Church follows two calendars depending on the patriarchates. There are patriarchates, for example, those of Moscow and Serbia, who celebrate them according to the Julian calendar, and therefore celebrate Christmas on January 7, that is, 14 days after December 25. There are others, for example, the patriarchate of Constantinople, to which the Greek Church belongs, the Romanian patriarchate or the Bulgarian patriarchate, who celebrate them according to the Gregorian calendar, that is, they celebrate Christmas and all fixed feasts as is done in the West.

Priest Martí Puche

Orthodox Parish of the Protection of the Mother of God - Patriarchate of Serbia