Roman Easter

The controversy over the correct date for Easter began in Early Christianity; reforming the date remains a topic of debate today.

Some see this first phase as mainly concerned with whether Christians should follow Old Testament practices, see also Christian views on the Old Covenant and Judaizers. Eusebius of Caesarea (Church History, V, xxiii) wrote:

Quartodecimanism, a word not used in Eusebius' account as he wrote in Greek, is derived from the Biblical Latin term for the practice of fixing the celebration of Passover for Christians on the fourteenth (Latin quarta decima) day of Nisan in the Old Testament's Hebrew Calendar (for example Lev 23:5). This was the original method of fixing the date of the Passover, which is to be a "perpetual ordinance". According to the Gospel of John (for example John 19:14), this was the day that Jesus was crucified in Jerusalem. (The Synoptic Gospels place the day on 15 Nisan, see also Chronology of Jesus.)

Irenaeus records the diversity of practice regarding Easter that had existed at least from the time of Pope Sixtus I (c. 120). He recorded Polycarp, the bishop of Smyrna, observing the fourteenth day of the moon, whatever day of the week that might be, following a tradition which he claimed to have derived from John the Apostle.

...
Wikipedia