Sister church

This article is part of a series on
Catholic–Eastern Orthodox relations
Overview
Catholic Church Eastern Orthodox Church
Schisms Acacian schism (484–519) Photian schism (863–867) Great Schism (1054–)
Reasons for the Great Schism Papal supremacy (differing views) Ecclesiastical differences Filioque (differing views) Theological differences
Further division motives Massacre of the Latins (1182) Sack of Constantinople (1204) Pratulin Martyrs (1874)
Medieval reunification attempts Council of Bari (1098) Second Council of Lyon (1274) Council of Florence (1438–1445) Bull of Union with the Greeks
Modern ecumenic relations Catholic–Orthodox Joint Declaration (1965) Balamand declaration (1993) Dominus Iesus (2000) Ravenna Document (2007) Havana Declaration (2016) Pope John Paul II's relations with the Eastern Orthodox Church Church of the Holy Sepulchre Eastern Catholic Churches Eastern Catholic liturgy Joint International Commission for Theological Dialogue Between the Catholic Church and the Orthodox Church Papal primacy Sister church
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Sister churches was a term used in 20th-century ecclesiology to describe ecumenical relations between the Roman Catholic Church and the Eastern Orthodox Churches, and more rarely and unofficially, between the Roman Catholic Church and the Anglican communion. The Catholic Church has since called on theologians to avoid the term, clarifying that "one cannot properly say that the Catholic Church is 'sister' of a particular Church or group of Churches. This is not merely a question of terminology, but above all of respecting a basic truth of the Catholic faith: that of the unicity [uniqueness] of the [Catholic Church]." The term is also currently used among Protestants to refer to different denominations of the same religious tradition.