Catholicos (plural Catholicoi) is a title used by the Patriarch (head/regional head bishop) of any of certain Eastern churches. The word is a transliteration of the Greek καθολικός, pl. καθολικοί , meaning concerning the whole, universal or general.
A Catholicate or Catholicosate (at times spelt as catholicossate) is the area of responsibility (territorial or otherwise) of the catholicos, considered a leader within any of the several churches of Eastern Christianity, especially those regarded as Oriental Orthodoxy.
While a catholicos is sometimes considered to correspond to a bishop in the Roman Catholic and Protestant traditions, a catholicate is typically a larger and more significant organizational division than a bishopric, archdiocese or episcopal see. Catholicates often have distinct cultural traditions established over many centuries.
The title rose sometime after the establishment of the three ancient Patriarchs (of Rome, Alexandria and Antioch). It first seems to have been applied to the churches east of the Roman Empire in the Persian Empire, where it is believed to be in the succession of Apostle Thomas. According to Bar Hebraeus Apostle Thomas is the first in the succession in the East. However the historical evidences point to the fact that the office of the Catholicos of the East was founded in the early 5th century (410) when the Persian Church declared its autonomy. Thus the Catholicos of the East became the head of the Persian church.
The area of influence of a catholicos is a catholicate. Some are listed below.
Towards the end of the 5th century a Christology based on the teachings of Nestor split the Persian Church with one section forming an autocephalous Catholicate of the East (which later came to be known as Patriarchate) and another section retaining its ancient ties with the Patriarchate of Antioch. The Church organised under the autocephalous Catholicate came to be known as Assyrian Church with its flock mainly in Iraq and diaspora. At present there are three Catholicates or Patriarchates in the Church of the East - the Chaldean Catholic Church having reunited with the Pope and rejected Nestorianism.
The current Seat of the Catholicos, the head of the Assyrian Church of the East is in Chicago, Illinois, USA.
The historic office of the canonical Orthodox Catholicate of the East within the Oriental Orthodox Church came to be later known as Maphryono (Anglicized as Maphrian; meaning Fructifier) in Syriac following the split within Eastern Church due to Nestorian schism. Historically, the Maphryono ranks second in hierarchy of the Syrian Orthodox Church after the Patriarch of Antioch. At least seven of the Maphryonos have later been elevated as the Syrian Orthodox Patriarch of Antioch. This historic office of 'Maphryono' came to an end in a council of all the Syrian Orthodox Metropolitans presided over by the then Patriarch of Antioch in 1861.
In 1912 when a dispute erupted in the Indian church, one section of the Church in India declared the revival of this office and thus starts the new history of the Catholicate in India. Thus begins the history of two Orthodox Churches in India with one faction remaining in unity with the ancient Syrian Church of Antioch while the other faction declaring as autocephalous Church. From 1964 there is a brief era of unity between both factions but a decade later the two factions again started to function as two independent Orthodox churches, each having its own Catholicoses and Church administration.
The Catholicos is the legal and canonical head of Catholicose of the East (a decision supported by the Supreme Court of India) and the Malankara (Indian) Orthodox Syrian Church.
The Catholicos of the Indian Orthodox Church presides over the Holy Episcopal Synod (the college of bishops) and is vested with the prime jurisdiction regarding the temporal, ecclesiastical and spiritual administration of the Indian Orthodox church. The Malankara Orthodox Church holds the view that it was the pre-Nestorian Catholicate, with its autocephalous rank, that was revived in the East for the Orthodox in the 6th century by Mar Yakub Burdana and relocated to India in 1912. The Church's tradition holds that it was a part of the ancient succession in the East which begins with Apostle Thomas.
Catholicos Baselios Marthoma Didymus I is currently the legal and canonical Catholicose of the East.
The Catholicos is the head of the Catholicate of the Syrian Orthodox (Jacobite) Church. He is also the Metropolitan Trustee of the Jacobite Syriac Christian Association, a representative body of the Malankara Syriac Orthodox Church. The catholicos presides over the Holy Episcopal Synod of the Universal Syrian Church in India. The Catholicos of the Universal Syriac Orthodox Church, who is also sometimes referred as Maphryono, ranks second to the Patriarch of Antioch and all the East in hierarchy of the Universal Syriac Orthodox Church.
Aboon Mor Baselios Thomas I is presently the canonical Catholicos and the head of the Syriac Orthodox (Jacobite) Christians in India.
Likewise, the heads of other major churches outside of the Roman Empire also bore the title Catholicos. The title is used in the Armenian Apostolic Church, which is one of the Oriental Orthodox churches. The Catholicos of All Armenians presides over the Supreme Spiritual Council (the Armenian Church's governing college of bishops), and is the head of the world's 7 million Armenian Apostolic Christians.(Autocephalous Church of the Oriental Orthodox Church)
The Catholicos is also sometimes called the "Catholicos of Etchmiadzin" after the city that is his see.
The Current Catholicoss of Armenia and All Armenians is Karekin II (1999-Present)
The Catholicos also sometimes known as the "Catholicos of the Great House of Cilicia" is Aram I (1995-Present)
Following the Eastern church tradition of its sister church the Armenian Apostolic Church, the head of the Armenian Catholic Church (in communion with Rome), carries the title Catholicos-Patriarch of Cilicia.
The Armenian Catholic Church is an Eastern Catholic church sui juris within the Catholic Church. It historically represents a schism from the Armenian Apostolic Church. It is in full communion with and accepts the authority of the Pope in Rome as regulated by Eastern canon law. The church uses the Armenian Rite and Armenian language in its liturgy. The present head of the Church is Catholicos-Patriarch Nerses Bedros XIX, with the full title being officially "Patriarch Catholicos of the House of Cilicia"
The Syro-Malankara Catholic Church is an autonomous church in India. It regained its communion in 1930 with the Roman Catholic Church. In 2005 it was elevated to the status of a Major Archiepiscopal Church. The major archbishop has since used the term "Catholicos", the Oriental equivalent. Catholicos is equivalent to a Major Archbishop in the Catholic Church. The Major Archbishop Catholicos Baselios Cleemis is the present Catholicos of the Syro-Malankara Catholic Church. He is addressed as "His Beatitude"; adherents use the honorific "Moran Mor".