Why does Easter move around the calendar?

The controversy over the dating of Easter

Unlike Christmas and Thanksgiving, the dating of Easter changes from year to year. Sometimes Easter is in March and sometimes it is in April. But why isn’t one date chosen like other holidays? This uncertainty is not new and dates back to the time of the early church. Within a hundred years of Jesus’ resurrection, Christians were already at odds over when to celebrate that event. The main twist involves those who wanted to celebrate Easter on the day Jesus arose, a Sunday, and those who wanted to celebrate it on Passover, regardless of which day it fell during the week.

The earliest disagreement went by the unusual name of the Quartodecimian Controversy. The origin of the name is actually simple. The Passover always occurred on the Jewish date of Nisan (or Nissan) 14. Thus the name, Quartodecimian, was derived from the number 14 ("quartus" or 4 and "decius" or 10). Those holding to this view believed Easter should be celebrated on the same day as the Jewish Passover.

The Passover itself always occurred on a full moon. But how did the Jews ensure that Nisan 14 would fall on a full moon? Because the Jews used a lunar calendar and not a solar calendar. Our solar calendar measures the time it takes the earth to rotate around the sun once. But the Jews used a lunar calendar, one month being the time it takes the moon to go around the earth once. The first day of a Jewish month was the day following a new moon (when the moon is completely dark). That way 14 days after the new moon was always a full moon; therefore the 14th of Nisan—or of any Jewish month—was always a full moon.

So the Quartodecimian Christians—who mainly lived east of Italy in Asia Minor—wanted Easter celebrated on the same day as the Passover, no matter on which day of the week it fell. But this caused a problem because many Christians in the West—think Europe—wanted Easter celebrated only on a Sunday, the actual day on which Jesus arose. We can date this controversy to the year 155. Polycarp, Bishop of Smyrna, traveled to Rome in that year to discuss certain issues with Pope Anicetus; included was the differences in the dating of Easter. Polycarp (from Smyrna in Greece, east of Italy) was a Quartodecimian. He tried to persuade Anicetus to make this dating scheme standard in the European churches but Anicetus declined to enforce this. Yet Anicetus did not force the Quartodecimians to change their practice.

So Easter from early on was celebrated at different dates in different regions of the Roman Empire. A Church Council was called in 325 to deal with different issues in the early church, among them the dating of Easter. In order to standardize the date of Easter, the decision was made to establish Easter on the first Sunday after the full moon after the vernal equinox (March 21). This solution satisfied both sides, those wanting to celebrate Easter on a Sunday and those wanting to celebrate Easter on a full moon (or close to it) as when Jesus resurrected.

It took awhile for all the churches to align with this decision. From Ambrose (337-397; he was a bishop) we learn that as late as the year 387 Easter was observed in present day France on March 21, in Italy on April 18, and in Alexandria, Egypt on April 25. Eventually, though, Easter was celebrated on the same date: the first Sunday after the first full moon after March 21.

But Passover and Easter are still linked. Here’s how. Remember that because the Jewish calendar is lunar, the 14th of each Jewish month is a full moon. Therefore, since Easter is celebrated on the first Sunday after the full moon after the vernal equinox, and Passover is celebrated on the full moon after the vernal equinox, then Easter is celebrated the Sunday after Passover. And when the full moon is the night before Easter, both celebrations occur on Easter Sunday.

©2004 Mark Nickens All Rights Reserved