My wife and I had a discussion last night concerning the different time periods we actually celebrate Easter. Sometimes, Easter is in mid-April, and sometimes in early March. We celebrate the birth of Christ on Dec. 25 every year, yet there's no definitive date to celebrate his death and resurrection. Is this because history has never been able to pinpoint exact dates for these important events in our religious and faith history? I think most Christians would prefer to celebrate both events on specific dates.
-- B., via email
Yours is a valid and fascinating question with a complicated answer. Easter, unlike Christmas, is connected to Judaism in direct ways. Because the crucifixion and resurrection of Jesus occurred after Passover, it obviously makes no historical sense to set a fixed date for Easter, which might then occur before Passover in some years.
Since the Jewish calendar (and by the way, the Muslim calendar, as well) is calculated on a lunar basis, Easter had to be connected to the cycles of the moon, as well. Passover is celebrated on the 15th day of the spring month named Nisan.
There's a good reason why all religious calendars, from the most ancient, follow a lunar pattern. It's easy to track the monthly phases of the moon, while it's virtually impossible to track the cycles of the sun through the seasons.
Solar calendars did not become normative until astronomical calculations became more advanced and precise. The problem with lunar calendars is that a lunar year is about 11 days shorter than a solar year, so adjustments need to be made for all lunar holidays that are also seasonal holidays so they always fall in the proper season of the year.
Passover and, by extension, Easter, must occur in the spring, and that's why the lunar calendar must be adjusted periodically. Judaism does this by occasionally adding an additional month called Adar in the spring. Islam is unique in that it does not adjust for the shorter lunar year. Ramadan moves in the Gregorian (solar) calendar about 11 days every year. The date may also vary from country to country, depending on whether the moon has been sighted or not. One of my favorite Muslim blessings is, "May you be privileged to celebrate Ramadan in every season of the year."
Easter is celebrated on the first Sunday after the paschal new moon. This is roughly, but not exactly, the first new moon after the vernal equinox in the spring. However, because Western Christianity follows the Gregorian calendar and Easter Orthodox Christianity follows the Julian calendar, there's a difference between the dates of Easter in these two Christian traditions.
Easter basically can fall any time after Passover from the end of March to the end of April. Eastern Orthodox Easter cannot occur before April 2.
The larger spiritual and natural issues related to your question go beyond arcane religious astronomical calculations. Easter links Christians and Jews in powerful ways.
After Christianity became the religion of Constantine and the West in AD 324, there was an effort to separate Christianity from its Jewish roots. Many Christians don't even realize that the Last Supper was, according to the accounts of the synoptic gospels of Matthew, Mark, and Luke, a Passover seder meal (see Mark 14:12). The Gospel of John has the crucifixion just before Passover (see John 19:14.) In any event, I still meet Christians who have no idea that Jesus and all his followers were Jewish. Christians can't come to grips with their modern identities without taking into account their ancient Jewish origins. The annual proximity of Easter and Passover ought to serve as a reminder that our God is the same God, and our histories are linked at their root and core. We are spiritual brothers and sisters not just this week but every week.
The dates of Easter and Passover also link us to the cycle of nature. By making the start of these holidays correspond to the start of spring, we're reminded that spiritual renewal and nature's renewal can intersect and be mutually sustaining.