Palm Sunday, Maundy Thursday, Good Friday, Holy Saturday and Easter Sunday: the feast days of Holy Week, the most important holiday of the Christian liturgical year and the most contentious week of the medieval Christian year. I actually had forgotten that it was Holy Week until I found myself, on Thursday by sheer coincidence, explaining the concept of transubstantiation--the moment in Mass when the wine and bread turn into the blood and flesh of Jesus Christ--as it related to the legend of the Holy Grail. You can all wake up now; I won't be talking about that.

Christmas has become an inclusive and heavily secularized holiday over the centuries, incorporating all sorts of syncretic, non-religious and even non-Christian customs and rituals. No one forgets or misses Christmas. Easter is the polar opposite of Christmas, and was even more so during the Middle Ages.

Easter and Passover (with which Easter is so intimately and controversially connected) probably have origins as spring festivals of some sort deep in ancient times. But Easter is as Christian as Passover is Jewish. Even taking the Easter Bunny into account, Easter is an intensely religious festival, so intense that it has divided Christians from each other and others as much as Christmas can bring them together. Anti-Jewish riots of the later Middle Ages, for example, often occurred during Holy Week. Unscrupulous and fanatical preachers would enter the Jewish quarters with Christian mobs and whip up anti-Jewish sentiment with stories of blood libel and the Jews murdering and mocking Christ on his way to the Cross. In frontier areas where significant non-Christian communities existed, Jews and Muslims frequently begged the local secular authorities (not always successfully) for protection and the right to close their gates to these mobs. For them, it was not a week of peace and renewal of faith, even when they were celebrating their own festivals, but one of fear and tension.

Medieval conflict among Christians over Easter seems to have centered around the legacy of Jesus Christ to his followers and the slow transition over the first five centuries or so in the Christian Era from Jesus the teacher and founder of Christianity to Christ the Redeemer and Son of God. While even sects like the Arians never saw Christ as an ordinary man called Jesus, the process of deifying Jesus was not nearly as certain or smooth as ordinary modern Christians--Orthodox, Catholic, Protestant and others--have been taught.

The fourth century controversy, exemplified by the Nicene Creed for example, centered around the true nature of Christ (purely human or purely divine), his position relative to God the Father, and his existence (or not) prior to his conception and birth to Mary. Those secularists who mock the arcane and convoluted nature of the Trinity, and the rather vague idea of the Holy Spirit, are generally unaware that these concepts reflect a major compromise between ferociously opposed segments of the early Church. Those who facilitated that theological compromise and prevented the Church from suffering a potentially fatal split so early in its history, no matter how personally combative and divisive themselves (like Cyril of Alexandria), were canonized and otherwise rewarded.

Then there was the Easter Controversy, which occurred because Easter is a floating feast--that is to say, it has no fixed date on the calendar. The first phase of the controversy occurred during the second century C.E. over what day of the week Easter should fall on. It was eventually established as Sunday.

The second phase began during the first Council of Nicea in 325 over which Sunday and whether or not all Christians should celebrate on the same Sunday. This controversy tended to have elements of central Church authorities versus regional churches. In the fourth century, for example, the "straying" church was in Syria.

The third phase kicked off when the Celtic/Insular church of Ireland and Britain duked it out with Roman authorities until the matter was finally resolved (albeit with much grumbling from the former) by the Synod of Whitby in 664. Easter is now established as the first Sunday of the first full moon that occurs after the 21st of March.