The Byzantine Church or Eastern Rite Catholics are Catholics, faithful to the Catholic magisterium. They are not “Orthodox”.
Catholicism is not intrinsically connected with any particular rite. It is practiced in a number of liturgical rites, both Roman and Eastern.
All Catholics are full-fledged Catholics.
The essence of being a Catholic consists in these three conditions: one must profess the same faith taught by our Lord, accept the seven Sacraments and recognize the Pope of Rome as the visible head of Christ’s Church on earth.
The four marks of the Catholic Church are that it is One, Holy, Catholic, and Apostolic.
Catholicism: Different expressions of One Faith
The Catholic Church began in Jerusalem and within 300 years the Church had grown to include people from many nations on earth. They were all members of the Catholic Church.
Every great nation in the Church expresses the “one faith” in different ways and with different customs. For example, they may celebrate the Mass (Divine Liturgy) in different ways; they all receive Christ in the Seven Sacraments (Holy Mysteries) but they are received exteriorly in different ways; feast days and times of fasting may be different too. Each local Church having its own special customs and ways of demonstrating and experiencing the One True Faith we call a Rite of the Catholic Church.
As missionaries traveled to different countries, they brought their rite with them and passed it on to the people they converted. These new Catholics treasured their rite and passed it on to their descendents. Whenever these people emigrated, the liturgical rites of their forebears were brought to their adopted countries.
How the Church Spread
In the apostles’ journeys to convert the Gentiles and establish Christ’s Church, they went out from Jerusalem to four important centers: Antioch, Alexandria, Rome and Constantinople. From Rome the one faith spread to Western Europe and is therefore referred to as the Roman, Latin, or Western Church. From Antioch, Alexandria and Constantinople, the faith moved through the Middle East and into Eastern Europe. These are therefore referred to as the Eastern Churches.
From the great Syrian city of Antioch came the following rites: Armenian, Chaldean, Melabarese, Malakarese, Maronite, and Syrian. The Chaldean Church originally came from Iraq, but Chaldean missionaries soon brought the faith to Persia (Iran) and India. They set up churches in China some 800 years before the time of St. Francis Xavier.
From Alexandria in Egypt, missionaries brought the Gospel to Sudan and Ethiopia. Those churches are the Coptic and Ethiopian rites.
The Roman or Latin Church developed in the city of Rome under the first Pope, Saint Peter. Missionaries of the Latin rite traveled all through Western Europe and converted the people of these countries to Christ. Most of the Catholic churches in America are of the Roman rite because most of the people who settled in America originated from the countries of Western Europe.
The Byzantine Church began in Byzantium or Constantinople (modern day Istanbul, Turkey). Originally the Byzantine Church was primarily in Greece and Turkey, around the great capital of the Byzantine Empire. Because the divine services were offered in Greek, the Church soon spread to the Greek speaking colonies in Albania, Sicily, Southern Italy and to Northern Europe. The Byzantine Church includes: Ukrainian, Albanian, Bulgarian, Croatian, Greek, Hungarian, Italo-Greek, Melkite, Romanian, Russian, and Ruthenian.