I HAVE read with interest the letters regarding the date of Easter.
Easter was the most important feast of the Christian Church and its place in the calendar determined the position of the rest of the church’s movable feasts. Because its timing depended on both the Moon’s phases and the vernal equinox, ecclesiastical authorities had to seek some way of reconciling lunar and solar calendars. Some simple form of computation, usable by non-astronomers in remote places, was desirable.
Further the Churches wanted Easter Day on a Sunday and it had to be in the week of the Jewish Passover to fit with the Bible’s accounts. After that it gets much more complicated and you can read this at www.britannica.com/eb/article-60230/calendar