Separation of Easter from the Jewish Passover
After the June 19 settlement of the most important topic, the question of the date of the Christian Passover (Easter), was brought up. This feast is linked to the Jewish Passover, as crucifixion and resurrection of Jesus occurred during that festival. By the year 300, most Churches had adopted the Western style of celebrating the feast on the Sunday after the Passover, placing the emphasis on the resurrection, which occurred on a Sunday. Others however celebrated the feast on the 14th of the Jewish month Nisan, the date of the crucifixion according to the Bible's Hebrew calendar. Hence this group was called Quartodecimans. The Eastern Churches of Syria, Cilicia, and Mesopotamia determined the date of Christian Passover in relation to the 14th day of Nisan, in the Bible's Hebrew calendar. Alexandria and Rome, however, followed a different calculation, attributed to Pope Soter, so that Christian Passover would never coincide with the Jewish observance and decided in favour of celebrating on the first Sunday after the first full moon following the vernal equinox, independently of the Bible's Hebrew calendar.
More...