The Early Christians
n“The early development of the celebration of Easter and the attendant calendar disputes were largely a result of Christianity's attempt to emancipate itself from Judaism. Sunday had already replaced the Jewish sabbath early in the second century, and despite efforts in Asia Minor to maintain the Jewish passover date of 14 Nisan for Easter [or, rather, the true Passover] (hence the name Quartodecimans [meaning ‘Fourteeners']), the Council of Nicaea adopted the annual Sunday following the full moon after the vernal equinox (March 21)”

- R.K. Bishop quote, Evangelical Dictionary of Theology, 1984, Editor: Walter Elwell, "Easter".