Eastern Christianity consists of four main church families:

(a) the Eastern Orthodox Church, which recognize the Patriarch of Constantinople;

(b) the Oriental Orthodox churches;

(c) the Assyrian Church of the East;  and

(d) the Eastern Catholic churches also called Byzantine Catholic, which are in communion with the Church of Rome and the Pope.

1. The Eastern Orthodox Church also called Orthodox Church has 300 million members.

The churches in Rome and Constantinople separated in an event known as the East–West Schism of 1054. In Rome, the church became the Roman Catholic Church (red line) and in Constantinople the church became the Eastern Orthodox Church (blue line).

Christians of the Eastern Churches call themselves Orthodox, examples are the Greek Orthodox Archdiocese in America, the Russian Orthodox Church and the Greek Orthodox Church of Constatinople. They are not in communion with Rome.

Rendering of Greek Orthodox Church National Shrine, currently under construction, at site of World Trade Center in NYC. Original church was destroyed by 911.

While Eastern Orthodox Christians have much in common with Eastern Catholics, they’re still in schism, split off from the Pope and therefore not Catholic.

Each Orthodox Church has a bishop, with a territory over which he governs. There is no central command like a pope in the Roman Catholic rite.

2. Oriental Orthodox Churches – 86 million members

The Assyrians and Orientals left the Orthodox Church in the years following the Council of Ephesus (431) and the Council of Chalcedon (451), in their refusal to accept those councils’ Christological definitions, which were based on St. Basil’s methodology and writings.

The Standing Conference of Oriental Orthodox Churches Annual Concelebrated Liturgy led by H.H. Mor Ignatius Aphrem

Oriental Orthodox icon.

3. Assyrian Church of the East – .6 million members
Headquarters in Erbil in Northern Iraq.

Coat of Arms of Assyrian Church of the East.

4. The Eastern Catholic Churches – 19 million members

Within Eastern Christianity are the Eastern Catholics that have their roots in the Orthodox East, with twenty three Eastern Churches in communion with Rome. They are autonomous self governing Eastern Catholic Churches. As an example, the Byzantine Catholic tradition is one of these and includes the Ukrainian Catholic Archeparchy of Philadelphia.

Aerial view of the Church of Transfiguration at the summit of Mount Tabor, which is divided into Eastern Orthodox (northeast) and Roman Catholic (southeast) areas.

Byzantine Catholic Churches include Ukrainian, Ruthenians, Melkites, Coptics and others.

Byzantine Ukrainian Church: Iconostasis of Uspenski Cathedral in Helsinki, Finland

Saint Mary’s Ukrainian Catholic Church, Alberta, Canada

The Byzantine Ukrainian rite, the largest of the eastern catholic churches has 4.5 million members or 26% of all Eastern Catholics.

The Pantocrator “Ruler of All” Christ blessing his people with New Testament in left hand, seated on a holy chair in the Cathedral of the Immaculate Conception, Philadelphia. The Pantocrator is central to Eastern Byzantine Catholics.