Published online by Cambridge University Press: 05 June 2012
Easter: see Calendar, Liturgical.
Eastern Catholic Churches The Eastern Christian Churches are divided into two groups: the Orthodox Churches and the Eastern Catholic (sometimes referred to as Uniate) Churches. Until the eleventh century, all Eastern Churches were visibly in communion with Rome, though as early as the fifth century Church unity had been weakened due to Christological, political, and cultural difficulties. In 1054, the eastern and western branches separated from one another. To this day, the former have been known as the Eastern Orthodox Churches, and the latter, the Catholic (or Latin) Church. The separation was visibly expressed by the Orthodox Churches' rejection of the western way of understanding the primacy of the Pope (see Papacy).
The Orthodox Churches include autocephalous (i.e., self-governing) groups, such as the Greeks, Russians, Ukrainians, Bulgarians, and others. Between the sixteenth and eighteenth centuries, various Orthodox communities within these autocephalous groups re-established communion with Rome. In this way, each of the Eastern Catholic Churches (except for the Maronite Church) has an Orthodox counterpart. Though they hold their eastern heritage in common with the Orthodox Churches (and, like the latter, continue to have their own patriarchs), they are in communion with the Holy See. These developments can be seen as part of papal attempts to secure unity with the Orthodox that date from the thirteenth century and continue today, most recently with the publishing of John Paul II's (r. 1978–2005) encyclical, Ut unum sint (1995).