There is once again renewed hope that ongoing ecumenical dialogue between the Greek Orthodox Patriarchate of Constantinople and the Roman Catholic Church will resolve an ancient rift.

That rift between the two halves of Christianity is over when Easter is celebrated.

Striving for unity

A decision by the Ecumenical Patriarchate of Constantinople, Bartholomew I, (with, one must imagine, the support of the Patriarchate of Alexandria and the Church of Greece) to adopt the Western Gregorian calendar could spell the end of division.

If so, Sunday (May 5) might be the last time that some Eastern Christians celebrate Easter on a different date than Westerners.

If such a decision is made, it will be one of the most significant moves in healing the nearly 1,000-year-old rift between the two ancient churches.

It will move the "Greek churches" further away from their Slavic Orthodox Christian brothers and closer to Rome.

It will also most likely further the deep, growing divide between the Patriarchate of Constantinople and the Patriarchate of Moscow.

Either way, it will be yet another turning point in the centuries-old battle over "the calendar," and the decision will not be merely practical or theological but will be the next chapter in the longest-running culture war in the West.

The Julian calendar

The culture war began in the early Middle Ages, by which time scholars were aware that the Julian calendar, the calendar that Christendom had inherited from the Roman Empire, had some problems.

Adding a day every 128 years, the Julian calendar didn't keep Easter, the important Christian feast that is calculated according to the spring equinox, from slipping down the calendar year, out of sync with the seasons.

The ordering of time became a fight about the ecclesiastical implications of scientific discovery and societal change, the role of geopolitics in shaping religious identity and the shifting borders of tradition and innovation.

It's why, over the centuries, figures no less famous than the Venerable Bede and Dante weighed in: Time is a theological problem as much as a scientific one.

Divisions grow

In 1326, the Byzantine astronomer and theologian Nicephorus Gregoras proposed a reform that would remedy the problem, but Andronikos II Palaiologos, the embattled Byzantine emperor, rejected the proposal.

The Schism of 1054, "the Great Schism," had already split Roman Christianity from Byzantine Christianity.

Then, less than 100 years before Nicephorus put his reforms forward, Western crusaders had sacked Constantinople.

If one part of the divided Christendom accepted changes to the calendar and another part did not, Andronikos feared, repair would be impossible.

Over the next two centuries, repair eluded the churches anyway.

Constantinople fell to the Ottomans. An attempted reunion of the two churches at the Council of Florence had failed.

In addition, a pesky German friar name Martin Luther had launched the Protestant Reformation, dividing Christianity into many more parts than two.

Resisting authority

By the time Pope Gregory XIII decreed changes to the calendar in 1582, in a papal bull titled "Among the Most Serious Matters," plenty of people had long since stopped taking orders from the bishop of Rome.

While Catholic countries adopted the Gregorian calendar, and even Elizabeth I's privy council initially looked favorably on its changes, her Anglican bishops, like many Protestant leaders, saw the reform as an attempt to restore papal authority over them.

Only in the 18th century, as Europe's religious wars began to subside, did Protestant countries make the change.

In the Orthodox world, the situation was even more complicated.

As the centuries wore on, a stubborn adherence to tradition and a belief in an "unchanging church" became hallmarks of an identity that was increasingly dominated by a sense of siege by Western Christians and Islam.

The Julian calendar was not just the calendar, but part of the unbroken legacy of the ancient world from which Orthodoxy claimed its legitimacy.

An uneasy compromise

In the early 20th century, as the Ottoman Empire collapsed and Imperial Russia gave way to communist revolution, many civil governments in emerging majority-Orthodox states adopted the Gregorian calendar.

The ecclesiastical authorities refused to yield, however

The first crack in the church's united front came in May 1923, when the Council of Constantinople, convened by Greek Orthodox Patriarch Meletius Metaxakis, adopted the Revised Julian calendar.

This was a compromise devised by a Serbian scientist who said it was more accurate than either the original Julian or the Gregorian calendars.

Its primary benefit, however, was that it lined up with the Gregorian calendar until February of 2800, all without any of the complications of seeming to obey the pope.

Many Orthodox churches, including the Russian Orthodox Church, rejected the move.

Worse, in churches that made the change to the revised calendar, conservative or anti-Western factions broke away from the Mother Church of Constantinople over what they saw as a grave heresy.

A compromise was eventually struck, stipulating that the date of Easter would continue to be set according to the "Old Calendar" for all Orthodox Christians, regardless of which calendar they used for other purposes.

This remains the status of Easter today everywhere in the Orthodox world, except for the Orthodox Church of Finland, which has adopted the Gregorian Easter.

Any shift away from this uneasy settlement will likely be seen a move toward Western modernity.

Virtually absent from the conversation are the practical concerns of having a calendar that accurately describes observable astronomical facts.

Of course, this is true of most culture war issues, which by definition require us to abandon reason in favor of taking a a position on who we are and who we are not. If a battle over calendars strikes us absurd, we might have something to learn from this unfinished business.

• First published in Religion News Service.
• Katherine Kelaidis, a research associate at the Institute of Orthodox Christian Studies in Cambridge, England, is the author of "Holy Russia? Holy War?" and the forthcoming "The Fourth Reformation."

Several attempts, often led by Orthodox bishops, have been made over the past 100 years to push for a common date for Easter. It seems most Christians agree in principle but picking the date or the calendar or the formula has been elusive.

Different Christian communities celebrated Easter on different days until the Council of Nicaea in 325. That council decided that for the unity of the Christian community, Easter would be celebrated on the first Sunday after the first full moon after the spring equinox.

But the Julian calendar, used by Christians in the fourth century, was out of sync with the actual solar year. So March 21 — generally assumed to be the date of the northern hemisphere's spring equinox — gradually "drifted" away from the actual equinox.

In 1582, Pope Gregory XIII, relying on the work of the best astronomers of his time, reformed the calendar. He dropped 10 days, making the equinox fall on March 21 again.

But Orthodox Christians continue to use the Julian calendar to calculate the Easter date instead of the Gregorian calendar. Because the Julian calendar calculates a slightly longer year, it is currently 13 days behind the Gregorian calendar.

Orthodox Archbishop Job Getcha of Telmessos suggested that the year 2025would be a good year to introduce this calendar reform. That year will be the 1,700th anniversary of the First Ecumenical Council of Nicea.

The First Council of Nicea, held in 325, decided that Easter would be celebrated on the first Sunday after the full moon following the beginning of spring. That made the earliest possible date for Easter March 22 and the latest possible April 25.

Speaking with the Swiss news agency Kath.ch, Cardinal Kurt Koch welcomed the proposal. He said the anniversary of the Council of Nicea was "a good opportunity" for this change.

Cardinal Koch said, "I welcome the move by Archbishop Job von Telmessos. I hope it will meet with a positive response."

"It will not be easy to agree on a common Easter date, but it is worth working for," he stated. "This wish is also very dear to Pope Francis and also to the Coptic Pope Tawadros."

Sources

Catholic News Agency

Catholic Philly