Catholic-Orthodox church ecumenism

By Msgr. John Wynand Katende

Posted on: Wednesday,  17th June 2026

The name "Orthodox Church" originates from two Greek words: orthos (meaning "right" or "straight") and doxa (meaning both "belief" and "worship"). The term was first used by early Church Fathers to distinguish the mainstream, recognized Christian faith from teachings they considered heretical or heterodox.

Up until the 11th century, both the Eastern and Western halves of the Christian Church shared the same fundamental faith and considered themselves both "orthodox" (correct in doctrine) and "catholic" (universal). When the two regions formally split in 1054, the Western half became known as the Roman Catholic Church, while the Eastern half adopted "Orthodox" as its primary name. 

Why is Greek important to Christianity?

Christianity was largely based on Greek culture. Many of the world's first Christians were Greek, as were many Martyrs, Saints, and Church Fathers. The first churches on European soil were established in Greece. The Greek Saint Helen and her son, Saint Constantine, made Christianity the official religion.

The Greek language is the original written language of the New Testament. It provided the crucial linguistic bridge that allowed the early Christian message to transcend Jewish culture and spread globally throughout the Greco-Roman world. Philippi: Where Paul delivered his first sermon in Europe and established the first European church. Athens: Where Paul preached to the Athenians about the unknown God, bridging Greek philosophy and Christian theology.

Greek provided a highly nuanced, robust vocabulary that allowed early Christian writers to express deep spiritual and philosophical concepts with extreme accuracy. Foundational terms include Logos it used in the Gospel of John to describe Jesus as the divine "Word". Agape is used to distinguish the unconditional, sacrificial love of God from other forms of human affection. Ekklesia, used to translate into English as "church," literally means "called-out ones". It defined the Christian community as a gathering or assembly rather than just a physical building. 

Bridging the Old and New Testaments: The Septuagint is the ancient Greek translation of the Hebrew Bible, created centuries before the birth of Jesus. It played a major role in preparing Greek-speaking Jewish communities (and the broader pagan world) to understand the apostolic preaching and embrace Jesus as the Messiah.

It is t the bedrock language of early Christian theology. Early church leaders and theologians (such as Athanasius, Basil the Great, and John Chrysostom) wrote extensively in Greek. The foundational statements of Christian orthodoxy—including the Nicene Creed—were formulated in Greek.

Countries where the Orthodox Church is the majority are heavily concentrated in Eastern and Southeastern Europe and the Horn of Africa. Here, religion is interwoven in the local culture.

A divided Church is a big scandal. It is like a broken marriage. Churches need to turn to God, the great healer, in response to the priestly prayer of Jesus Christ (John 17:21). Spiritually and theologically, far more unites the Western and Eastern Churches than divides. Pope Francis emphasizes that the journey toward full communion should respect the diverse traditions of the two Churches.

Both churches use a hierarchical form of church government: bishops, priests, and deacons. In the Roman Catholic Church, the Bishop of Rome is called the Pope, and he is considered Christ’s representative as the head of the Church on earth.

The Eastern Orthodox Church is led by patriarchs, and each patriarch is the administrative head over the Orthodox Church in a given geographic region. These patriarchs are considered equals, with none having authority over another. The refusal of the Eastern Orthodox Church to defer to the will of the Bishop of Rome was a primary political factor in the Great Schism.

Roman Catholics and Orthodox agree on the doctrine of the Trinitarian nature of God. The Orthodox, however, reject the doctrine of the procession of the Holy Ghost from the Son as well as from the Father (“Filioque”), of the Nicene Creed. Both Churches honor Mary as the Mother of God. Both use icons in worship. But the Orthodox do not use statues.

The two Churches differ on the meaning of Easter. For Roman Catholics, Jesus saved man from sin through his death by crucifixion. For the Orthodox, salvation is achieved by Christ’s triumph over death in the Resurrection. Greek art doesn’t show the figure of the bleeding, crucified Christ. Orthodox cross themselves from right shoulder to left, Catholics from left to right.

There are seven sacraments in both the Roman Catholic and Eastern Orthodox churches. While the latter uses leavened bread for the Eucharist/holy communion, the former uses unleavened bread. The Eastern Orthodox Church believes that Jesus Christ is mystically present in communion, while the Roman Catholic Church believes that the bread and wine are transformed literally, but invisibly, into the Body and Blood of Jesus Christ.

The Greek Orthodox Bible has more books than the Catholic Bible; namely, Psalm 151 and 3 Maccabees.

Catholics and Orthodox Christians both celebrate Easter (Pascha) and Pentecost as their most sacred holidays, sharing the core theological meanings. However, they frequently observe these feasts on different dates due to distinct calendar systems, and they express the events through unique liturgical traditions, customs, and lengths of celebration.

The primary divergence is the date. The Catholic Church uses the Gregorian calendar, while most Orthodox Churches follow the Julian calendar, causing their Easter dates to occasionally align but often differ by up to a few weeks.

In Eastern traditions (including Eastern Catholic rites), Pentecost is considered a "Great Feast" of the highest rank. Churches are typically decorated with vibrant green branches and flowers, symbolizing new life in the Holy Spirit, and the liturgical color is green.

The Monday immediately following Pentecost is known as the Monday of the Holy Spirit. It is an official public bank holiday in Greece.

In Greece, Catholics are a minority, so their celebrations are generally quieter, church-based masses, often held in historical cathedrals (like those in Athens and Thessaloniki).

St. Paul exhorts Christians to “maintain the unity of the Spirit in the bond of peace” (Ephesians 4:3)