How is Roman Catholicism different from Eastern Orthodoxy?

Roman Catholicism and Eastern Orthodoxy share a common foundation in the Bible, historic creeds, and the decrees of early ecumenical councils, yet they differ significantly in governance, doctrine, and liturgical practice.12

Governance and Authority

The most fundamental difference lies in church polity. Roman Catholicism is highly centralized under the papacy, with the pope serving as the visible head of the church. Conversely, Eastern Orthodoxy consists of autonomous national churches that operate under the principle of "autocephaly." The ecumenical patriarch of Constantinople is considered "first among equals" but lacks the universal jurisdiction claimed by the Roman pope.213

Doctrinal and Liturgical Differences

• The Filioque: A primary dogmatic disagreement concerns the procession of the Holy Spirit. The Roman Catholic Church includes the phrase "and the Son" (Filioque) in the Nicene Creed, a practice rejected by the Eastern Orthodox.14
• Papal Doctrines: Roman Catholicism holds specific dogmas formulated in the 19th and 20th centuries, including papal infallibility, the Immaculate Conception, and the Assumption of the Virgin Mary.2
• Clergy and Sacraments: While both traditions value the seven sacraments, they differ in practice. Eastern Orthodox clergy may marry before ordination (though bishops must be celibate), whereas the Latin-rite Roman Catholic clergy generally practice celibacy. Additionally, Eastern churches use leavened bread for the Eucharist, while the Roman church uses unleavened bread.145