This is a question many Christians—and even non-Christians—have wondered about. Christmas is always on December 25th, year after year, without fail. But Easter Sunday and Good Friday seem to "move around" the calendar every year. Why is that?
Christmas Is Tied to the Solar Calendar
Christmas commemorates the birth of Jesus Christ, and the Western Church fixed this celebration on December 25th—a date on the standard Gregorian (solar) calendar that most of the world uses today. Because this calendar is based on the Earth's orbit around the sun, December 25th always falls in the same seasonal position every year. Simple, consistent, and fixed.
Easter Is Tied to the Lunar Calendar
Easter, on the other hand, follows an entirely different system. The date of Easter is based on the lunar calendar—specifically, it is calculated as the first Sunday after the first full moon following the spring equinox (around March 21st). This rule was formally established at the Council of Nicaea in 325 AD.
Since the lunar cycle does not align perfectly with the solar calendar, the full moon falls on a different date each year—which means Easter can land anywhere between March 22nd and April 25th.
Good Friday, being exactly two days before Easter Sunday, naturally moves along with it.
Why Was Easter Connected to the Moon?
This is rooted in the Jewish calendar. Jesus was crucified during Passover (Pesach), which is itself a lunar-based Jewish festival observed on the 14th of Nisan. The early Church wanted to honor this deep connection between the Last Supper, Passover, and the Resurrection—so they kept the lunar calculation rather than fixing it to a static solar date.
In short, Easter moves because Passover moves, and Passover moves because it follows the moon.
Has Anyone Tried to Fix Easter to a Permanent Date?
Yes! There have been several proposals over the decades to fix Easter to a set date—such as the second Sunday of April—to make it easier for families, schools, and businesses to plan. The idea has been discussed between Catholic, Protestant, and Orthodox Church leaders. However, no universal agreement has been reached, as many traditions value preserving the ancient lunar connection to Passover.
Conclusion
Christmas is fixed because it is tied to the solar calendar. Easter and Good Friday move because they are rooted in the lunar calendar, intentionally linked to the Jewish feast of Passover—the very context in which Jesus was crucified and raised. Far from being an inconvenience, this moving date is actually a beautiful reminder that the death and resurrection of Jesus Christ are deeply woven into the ancient story of God's redemption of His people.
"For Christ, our Passover lamb, has been sacrificed." — 1 Corinthians 5:7
