by Borgna Brunner
Easter is not only a movable holiday but a multiple one: in most years Western Christian churches and Eastern Orthodox churches celebrate Easter on different dates. In 2015, for example, Easter will be celebrated on April 5 by Western churches and April 12 by Orthodox churches. But in 2014, the two celebrations occurred on the same date, April 20.
The theological inconsistency of two Easters has remained a thorny problem for the Christian Church. "It has long been recognized that to celebrate this fundamental aspect of the Christian faith on different dates," states the World Council of Churches, "gives a divided witness and compromises the churches' credibility and effectiveness in bringing the Gospel to the world."
The formula for Easter—"The first Sunday after the first full moon on or after the vernal equinox"—is identical for both Western and Orthodox Easters, but the churches base the dates on different calendars: Western churches use the Gregorian calendar, the standard calendar for much of the world, and Orthodox churches use the older, Julian calendar.
That much is straightforward. But actually calculating these dates involves a bewildering array of ecclesiastical moons and paschal full moons, the astronomical equinox, and the fixed equinox— and that's in addition to the two different calendar systems.
The two churches vary on the definition of the vernal equinox and the full moon. The Eastern Church sets the date of Easter according to the actual, astronomical full moon and the actual equinox as observed along the meridian of Jerusalem, site of the Crucifixion and Resurrection.
The Eastern Orthodox Church also applies the formula so that Easter always falls after Passover, since the Crucifixion and Resurrection of Christ took place after he entered Jerusalem to celebrate Passover. In the Western Church, Easter sometimes precedes Passover by weeks.
The Western church does not use the actual, or astronomically correct date for the vernal equinox, but a fixed date (March 21). And by full moon it does not mean the astronomical full moon but the "ecclesiastical moon," which is based on tables created by the church. These constructs allow the date of Easter to be calculated in advance rather than determined by actual astronomical observances, which are naturally less predictable.
This division between the Eastern and Western Churches has no strong theological basis, but neither is it simply a technical skirmish. As the World Council of Churches has noted, much of Orthodox Christianity is located in the Middle East, where it has frequently been the minority religion, and in Eastern Europe, where until recently it faced hostility from communist governments.
The emphasis on honoring tradition and maintaining an intact religious identity was therefore crucial. Seen in this context, changing the rules governing its most important religious holiday chisels away at the foundations of an already beleaguered religious heritage.
A meeting organized by the Council of World Churches (in Aleppo, Syria, March 5–10, 1997) proposed a solution thought to be favorable to both East and West: both methods of calculating the equinox and the paschal full moon would be replaced with the most advanced astronomically accurate calculations available, using the meridian of Jerusalem as the point of measure. Since that meeting, however, no further progress has been made and the problem remains.
Since the beginning of the 20th century, a proposal to change Easter to a fixed holiday rather than a movable one has been widely circulated, and in 1963 the Second Vatican Council agreed, provided a consensus could be reached among Christian churches. The second Sunday in April has been suggested as the most likely date.