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The importance of Easter 2025 for ecumenical dialogue, unity

Mark your calendars: there is a very important anniversary on our horizon, and it could have a profound effect on Christian unity.

Fresco from the Chora Church, Istanbul (Wikipedia/Gunnar Bach Pedersen)

In a recent interview with the Turkish media, the Ecumenical Patriarch of Constantinople stated that conversations are ongoing between Catholic and Orthodox Churches, about a possible agreement on the common celebration of Easter in 2025, which coincides with the 1,700th anniversary of the Council of Nicaea.

Pope Francis has also expressed his support for a unified Easter celebration between Eastern and Western Churches.

In Pope Francis’ May 6, 2022 audience with the members, consultors, and staff of the Pontifical Council for Promoting Christian Unity, there was a focus on an ecumenical celebration of the 1700th anniversary of the council of Nicaea. “The style and the decisions of the Council of Nicaea,” said Pope Francis, “should enlighten the current ecumenical journey and lead to practical steps towards the full restoration of Christian unity.” The various sub-topics discussed by those involved included the search for a common date of Easter between East and West.

The Council of Nicaea (325 AD), of course, laid the cornerstone for the orthodox understanding of Jesus Christ. And that foundation has stood ever since. The creed, born of controversy and division, became the “rule of faith” or “symbol of faith,” by which all Christians could join in unity. It was further developed at the second ecumenical council, at Constantinople (381 AD) and has carried on even in modern times as a connecting point where Christians — Catholic, Orthodox, and Protestant — can find essential unity.

Creeds serve as symbols of unity. They function as guardians against heresy, which divides. Creeds sanction doctrinal agreement and consensus. The common profession of the Nicene Creed has been a fruitful starting point in ecumenical discussions from the twentieth century through the present. With the goal of unity in mind, we turn to the issue of the roots of the controversy over the date of Easter.

There is unitive power in the celebration of Easter. In the second century, differences arose among Christians regarding the date of celebration of Easter. Some celebrated Easter on the 14th of the month of Nisan (which usually falls in March–April), on the Passover instead of Sunday, while others celebrated Easter on the following Friday and Saturday. The first were called “Quartodecimans” and had given rise to discussions and controversy among Christians. However, it was not easy to find agreement of the date of Easter, because of the various errors found in the Jewish Calendar. That calendar had been prescribed in the Book of the Jubilees two centuries before the Christian era, and was based on twelve lunar months of 29 and 30 days, therefore shorter by 11 days than the solar year. It was therefore necessary, every two or three years to add an intercalary month between the months of Adar and Nisan, called Veadar. Alexandria was the center of determining the Easter dates.

The exact text of the decree of the Council of Nicaea addressing the Easter controversy has not been preserved, but there is evidence proving that Nicaea indeed discussed and determined the date of a common Easter between East and West. Eusebius’s Life of Constantine (Book 3, chap. 18) has an important piece from the deliberations of Nicaea, showing that it was resolved by the united judgment of all present, that this feast [Easter] ought to be kept by all and in every place on one and the same day.

Moreover, Theodoret of Cyrus (AD 455) in his Ecclesiastical History reported the good news of Nicaea of the common date for the celebration of Easter, stating:

the celebration of the most holy paschal feast was unanimously rectified, so that our brethren of the East, who did not previously keep the festival at the same time as those in Rome, … will henceforth celebrate it with you.

The deliberations of Nicaea for a common Easter date seemed straightforward and simple to apply. But, in reality, it was not accepted and consequently not applied, which caused the Easter controversy to continue and Christians to celebrate Easter apart. The date depended on two different calculations of the spring equinox. Alexandria calculated it on March 21, while Rome followed another criterion, and the date of the equinox could vary from March 18 to 25. Further complex details in the calculation methods followed in Alexandria and Rome perpetuated and exacerbated the disparities in the dates.

The controversy and divisions continued among Christians living in Syria, Mesopotamia, and part of Cilicia as well. The Easter controversy was so heightened that Canon 1 of the Synod of Antioch in Encæniis (AD 341) undertook some extreme measures to ban division by excommunicating both lay and clergy who championed divisions and ignored Nicaea’s deliberations.

Unfortunately, the date of Easter remained a point of contention, and Easter, instead of being the Feast of Feasts, uniting Christians in the mystery of the Resurrection, became a point of discord.

The difference in the dates on which the Eastern and Western Church celebrate Easter has to do with two different calendars, the time and date of the spring equinox, and the full moon. Eastern Christians follow the Julian calendar in calculating the date of Easter, and Western Christians follow the Gregorian calendar. This results in Christians celebrating Easter on different Sundays in most years.

The Gregorian calendar, designed to adjust for inaccuracies that were introduced by the Julian Calendar, went into effect on October 4, 1582. According to the Gregorian or the New Calendar, the dates were rearranged so that the equinox would fall either on March 20 or 21, as in the time of Nicaea.

Pope Gregory XIII, for whom the Gregorian Calendar is named, made great effort to put into practice the deliberations of the Council of Trent. The focus was Christian unity in the celebration of Easter, by revisiting the deliberations of the Council of Nicaea. To this end, he nominated a committee of experts and scholars with the task of investigating and approving a reformed calendar. The new system curbs the drift of the date of the equinox so effectively that the calendar will not lose a single day on the sun in well over 2,000 years. The new calendar is similar to the Julian calendar, but has special measures built in to adjust for small amounts of inaccuracy that would creep in over the centuries, thereby preserving the scientific accuracy of the Gregorian Calendar.

Luigi Lilio (often written Giglio; Latinized as Aloisius Lilius) is known as the primus auctor of the new calendar. Modern astrophysics and science are behind this calendar, whose pillars are the alliance of faith, reason, and science. The most important mystical event for the Catholic Church, the Resurrection of Jesus Christ, prompted research on how to find the correct date, and it was what led to this extraordinary calendar. The mystical conception of time, on the other hand, focuses synchrony on a single day: the spring equinox, to which the date of the Resurrection of Jesus Christ is linked. As Italian physicist Antonino Zichichi, from the Pontifical Academy of Sciences, former President of the World Federation of Scientists, of the European Physical Society and of Italy’s National Institute of Nuclear Physics, put it: “the perfect calendar and science could have been the triumph of atheist culture; instead, they were born in the heart of our culture.”

The question of a common date for Easter for Eastern and Western Christians was addressed in two documents of the Second Vatican Council in the appendix to the Constitution on the Sacred Liturgy, which stated:

The Sacred Council would not object if the feast of Easter were assigned to a particular Sunday of the Gregorian Calendar, provided that those whom it may concern, especially the brethren who are not in communion with the Apostolic See, give their assent.

The same desire to accommodate was expressed in the Decree on Eastern Catholic Churches.

In March 1997, an important consultation sponsored by the World Council of Churches and the Middle East Council of Churches met in Aleppo, Syria, and issued a statement, “Towards a Common Date for Easter”. The statement, which calls attention to the centrality of Christ’s Resurrection as a sign of Christian unity, recommended maintaining the norms established at Nicaea: that Easter should fall on the Sunday following the first vernal full moon, to calculate the astronomical data (the vernal equinox and the full moon) by the most accurate possible scientific means and using as the basis for reckoning the meridian of Jerusalem, the place of Christ’s death and resurrection. For now, by celebrating the Easter on separate dates, Eastern and Western Christians dilute and divide the Christian message.

Pope John Paul II, taking advantage of the common day of Easter of 2001 for Eastern and Western Christians, raised the ecumenical question of finding ways to celebrate Easter on a common day every year:

 Our people rightly insist that the celebration of Easter should no longer be a cause of division. Since the Second Vatican Council, the Catholic Church has shown herself favourable to every effort to re-establish the common celebration of the Paschal Feast. Yet this process seems more difficult than anticipated. Is it perhaps necessary to envisage intermediate or gradual stages, in order to prepare minds and hearts for the implementation of an arrangement acceptable to all Christians of East and West?

Now, on the horizon in 2025, we again have an opportunity to overcome this division in the celebration in the greatest of Christian feasts.

The coincidence of celebrating Easter on the same day in 2025 is an opportunity to return to what science and astronomy suggest. I see science and theology, reason and revelation making a case for a change of the Easter date calculation, not to conform with Rome or with the West but with more sound and accurate scientific calculation. The division of Eastern and Western Christians on the date of Easter also reflects the broader problem of their centuries-long separation from one another.

The Jubilee Year 2025, the 1,700th anniversary of the Council of Nicaea and the year with a common day to celebrate Easter in East and West, might be the perfect triple occasion to return to common Easter, or to the full exchange of gifts between East and West. As we celebrate the start of this holiday season, we may reasonably look backward and forward in gratitude for Christian unity that was and is to come.

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About Ines Angeli Murzaku 29 Articles
Ines Angeli Murzaku ( is Professor of Ecclesiastical History at Seton Hall University in New Jersey, Director of Catholic Studies Program and the Founding Chair of the Department of Catholic Studies at Seton Hall University. She earned a doctorate of research from the Pontifical Oriental Institute in Rome part of the Pontifical Gregorian University Consortium and has held visiting positions at the Universities of Bologna and Calabria in Italy and University of Münster in Germany. She is a regular commentator to media outlets on religious matters. She has worked for or collaborated with the Associated Press, CNN, Catholic World Report, National Catholic Register, Voice of America, Relevant Radio, The Catholic Thing, Crux, The Record, The Stream, Vatican Radio (Vatican City), and EWTN (Rome). Dr. Murzaku is currently writing a book on St. Mother Teresa entitled Mother Teresa: The Saint of the Peripheries who Became Catholicism’s Center Piece to be published by Paulist Press in 2020.


  1. Interesting and hopeful. Note, achieving unity would not require a single liturgy for the Mass, only that all acceptable forms have an Offertory, Consecration and Communion. It would require that all sects accept a single Pope. It is inconceivable that the Eastern Rite Churches would ever accept Francis, or anyone in his mold.

  2. Also, don’t we simply LONG FOR Catholic, Orthodox and Protestant hierarchs to agree on a single numeration of the Psalms.

    This and other simple adjustments (such as using the same calendar) would help the world to realize we followers of King Jesus Christ are unified by our deference to each other.

    It’s getting real late in the day; Christ can return any moment. Isn’t it time to put our house in order . . .

    Blessings to all who love God; from marty

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