Billy Kennedy: Why the date of Easter will continue to change each year

The Good Friday crucifixion of Jesus Christ and His joyful Resurrection on Easter Sunday morn is central to the Christian message and is a time for believers to reflect and move forward with a positive espousal of their faith. There may be religious and social advantages in universally marking Easter over a specific weekend. However, for reasons of culture, tradition and strict interpretation of calendar dates, leaders of Christianity across the globe are unlikely to agree. There have been unsuccessful attempts to have all Christians observe Easter on the same dates each year. It is generally accepted that modern-day Easter is derived from two ancient traditions - Judeo-Christian and pagan. Both have celebrated death and Resurrection themes after the Spring Equinox for 2,000 years.

Easter is not celebrated on the actual anniversary of Jesus Christ’s Resurrection (April 3, 33 AD is the most accepted date by reliable historians) and, among Christians in Western society, it may fall anytime between March 22 and April 25. This year it is April 1; last year it was April 16, next year April 21. Since the 325 AD, Easter Day has been the Sunday after the first full moon — known as the ecclesiastical paschal full moon — that falls following the vernal equinox, beginning of spring.

Eastern Christianity (Orthodox churches) use the Julian Calendar, which is currently delayed by 13 days from the Gregorian Calendar that Western Christians use. Easter is observed in Eastern countries, like Russia and Greece, between April 4 and May 8.

The Spring equinox occurs each year on March 20, 21 or 22 and Western Christians mark Easter on the Sunday on or after the full moon after the Equinox date - March 21. The ‘full moon’ is not the actual astronomical event; it is on the 14th day of the month according to a lunar calendar.

So, whatever the historical complexities of Easter. finding parity on set dates will still generate intense debate.