Catholic, Orthodox and Protestant Christianity: key differences

For its first thousand years, Christianity was broadly one church, though with tensions between the Greek-speaking East and the Latin-speaking West. In 1054, mutual excommunications between Rome and Constantinople marked the Great Schism, separating the Catholic Church in the West from the Orthodox Church in the East.

In the sixteenth century, reformers such as Martin Luther, John Calvin and Ulrich Zwingli challenged Catholic teaching and practice, leading to the Protestant Reformation. Lutheran, Reformed, Anglican and Anabaptist churches emerged, followed later by Methodist, Baptist, Pentecostal and many independent churches.

All three traditions affirm one God in three persons, the incarnation, death and resurrection of Jesus, the Bible as God’s word, baptism, and the hope of resurrection and eternal life. Most accept the Nicene Creed, though Orthodox Christians reject the Western addition known as the filioque.

Catholic teaching holds that authority rests in scripture and tradition, interpreted by the magisterium, the teaching office of the bishops in communion with the Pope. The Pope, as bishop of Rome and successor of Peter, has supreme authority, and under specific conditions his solemn definitions are considered infallible.

Orthodox Christianity also holds scripture and tradition together, but authority is expressed through the bishops and ecumenical councils. The Patriarch of Constantinople has a primacy of honour, not jurisdiction over other churches.

Protestant churches emphasize sola scriptura: scripture is the final authority over church tradition. Protestants have no single central authority, which partly explains their diversity.

Catholic teaching holds that salvation comes by God’s grace, received through faith and baptism and lived out in love, with the sacraments as ordinary means of grace. Orthodox teaching describes salvation as theosis, a lifelong process of union with God through grace, prayer and the sacraments.

Classic Protestant teaching emphasizes justification by grace through faith alone, sola fide: believers are declared righteous because of Christ, not their works, though good works follow from faith. In 1999, Lutheran and Catholic representatives signed a joint declaration finding substantial agreement on justification.

Catholic and Orthodox churches recognize seven sacraments, which the Orthodox call mysteries: baptism, confirmation or chrismation, the Eucharist, confession, marriage, ordination and anointing of the sick. Both believe that the bread and wine of the Eucharist truly become the body and blood of Christ.

Most Protestant churches recognize two sacraments instituted by Christ: baptism and the Lord’s Supper. Views of the Lord’s Supper range from Lutheran belief in Christ’s real presence to understandings of it as a memorial. Baptists and many evangelicals baptize only believers who profess faith, not infants.

Catholic and Orthodox Christians venerate Mary as the Mother of God and ask the saints to pray for them. Catholic teaching defines the Immaculate Conception and the Assumption of Mary as doctrines. Orthodox Christians honour Mary deeply and celebrate her Dormition, but do not define the Immaculate Conception.

Most Protestants honour Mary as the mother of Jesus but reject praying to saints, emphasizing Christ as the only mediator.

Orthodox worship centres on the Divine Liturgy, with icons, chant and incense. Catholic worship centres on the Mass. Protestant worship ranges from formal liturgy in Anglican and Lutheran churches to informal services focused on preaching and music in evangelical and Pentecostal churches.

Catholic priests in the Latin Church are generally celibate; Orthodox priests may marry before ordination, though bishops are celibate. Protestant ministers may marry, and many Protestant churches ordain women, which Catholic and Orthodox churches do not.

Catholic, Orthodox and Protestant Christians share the core of Christian faith. Catholics emphasize the authority of the Pope and the magisterium; Orthodox Christians emphasize conciliar tradition and theosis; Protestants emphasize the authority of scripture and justification by faith. They also differ on sacraments, Mary and the saints, and church structure.