Properly known as the Quartodeciman controversy (quartodeciman referring to the 14th day of the month)—or sometimes called the Passover-Easter controversy—the dispute, sometimes heated, centered on the proper day to celebrate Easter. When exactly were Christians to commemorate the resurrection of Christ Jesus?
Though we have every reason to believe the early church celebrated Easter from the apostolic age onward, the first explicit account of the celebration is recorded in the account of Polycarp’s (bishop of Smyrna) visit to Anicetus, bishop of Rome, around the year 155 to discuss the practice of Easter in the Eastern churches. At that time, the predominate practice in Asia Minor was to observe Easter on the fourteenth day of the Hebrew month of Nisan, coinciding with the date of the beginning of the Jewish Passover, regardless of the day of the week on which it fell. The Western practice, on the contrary, was to keep the feast on the Sunday following the Jewish Passover. Polycarp and the bishop of Rome failed to reach a consensus regarding the day of the celebration, yet the two parted company, agreeing to differ.
Over the next few decades, however, the incongruity between the East and West persisted, prompting Victor, bishop of Rome, to contrive synods in Rome, in Jerusalem, and in other regions of the Empire, hoping to quash the Eastern practice. When the churches in Asia Minor refused to reform their Easter practice, Victor excommunicated the congregations for not conforming to his desires.
Still not resolved, the issue continued to fester until Constantine became emperor, where he called together an ecumenical council in the town of Nicea in 325 to address two issues: primarily the Arian controversy but also a lesser known issue to history (but important to the early church, nonetheless), the proper date of Easter. Constantine wanted Christianity to be distinct from Judaism and did not want the celebration to coincide with the Jewish Passover. The council agreed and Easter was to be the first Sunday following the first full moon after the spring equinox. But there was still a problem. Churches throughout the empire had differing dates for determining the spring equinox, resulting in differing dates for Easter. Eventually, though, the council’s ruling was accepted that Easter would occur sometime between March 22 and April 25. Today, churches in the East and West still celebrate Easter on differing dates, since the West uses the sixteenth-century Gregorian calendar and the East kept the Julian calendar.