Catholicos (Gr. Katholikos, universal), ecclesiastical title of the Nestorian and Armenian patriarchs.
I. Nestorians.—During the first five centuries Seleucia in Mesopotamia, subsequently the see of the Nestorian catholicos, was under the Patriarchate of Antioch. In the fifth century, as can be seen in the “Synodicon Orientale” (ed. Chabot), almost all the bishops of Seleucia-Ctesiphon bore the title of catholicos, without, however, severing their relations with Antioch; hence, originally, the word catholicos was not synonymous with patriarch. Owing to the political separation of the East from the West and to theological disputes, several attempts were made during the fifth century to secure religious independence. In the synod held at Seleucia under Dadjesus in 424 (cf. Synodicon, 51, text, and 296, tr.) it was forbidden to appeal from the Catholicos of Seleucia to the Patriarch of Antioch. The breach, however, became complete and permanent under the Nestorian Mar Babai. The synod held under him (497 or 499) renewed the decree of independence from Antioch, and henceforth Seleucia became the center of Nestorianism. The list of the Nestorian catholicoi is given by Bar Hebraeus (Chronicon, ed. Abbeloos, and Lamy, III passim); the list is supplemented by the editors, III, 566 sqq. In the middle of the sixteenth century, in opposition to the Catholicos Mar Mama, several bishops met, elected Sullaka, and sent him to Rome for consecration. Since then there has been a Catholic patriarch whose residence is now at Mosul. A list of the catholicoi united with Rome is given by Abbeloos and Lamy, op. cit., 570 sqq. (See Nestorius and Nestorianism.)
II. Armenians.—Among the Armenians also catholicos was originally a simple title for the principal bishop of the country; he was subordinate to the See of Caesarea in Cappadocia. The bishops of Albania and Georgia, although dependent on the Catholicos of Armenia, bore the same title. Under King Pap and the Catholicos Iousik Armenia asserted its independence of Caesarea. In the fifth century the Armenians adopted Monophysitism and anathematized the Council of Chalcedon, 491. Many of the catholicoi, however, especially after the Crusades, professed the orthodox Catholic Faith. The see of the Armenian catholicos, originally Achtichat, has varied considerably. Besides many schisms have taken place, and today there are no less than five Armenian catholicoi. One of them, the successor of the, old catholicos, is at Sis in Cilicia, with jurisdiction over the Turkish provinces of Asia. His power in ecclesiastical matters, supreme in theory, is considerably curtailed in practice by the appointment of a catholicos with additional civil powers in Constantinople. Since 1113 there is also an Armenian catholicos at Aghtamar with jurisdiction over the island of that name and the villages surrounding Lake Van. Another catholicos resides in Jerusalem, but with greatly reduced powers. In 1441 another schism occurred, and a catholicos was elected in Etchmiadzin in Greater Armenia. Today he bears the title of “Supreme Patriarch and Catholicos of all Armenians”, and, at least theoretically, is considered the principal catholicos by all non-Catholic Armenians. Since 1740 there has also been a Uniat catholicos in Constantinople with the title of Patriarch of Cilicia. He is recognized by the Porte as having jurisdiction over all Catholic Armenians in the Turkish possessions. (See Armenia; Constantinople.)
In the beginning of the fourth century Albania and Georgia (Iberia) were converted to Christianity by Armenian missionaries, and the principal bishop of each of these countries bore the title of catholicos, although neither of them was autocephalous. They followed the Armenians in rejecting the Council of Chalcedon. At the end of the sixth, or beginning of the seventh, century the Georgian catholicos asserted his independence and came back to orthodoxy. Henceforward the Georgian Church underwent the same evolutions as the Greek. In 1783 Georgia abolished the office of its catholicos, and placed itself under the Holy Synod of Russia, to which country it was united politically in 1801. The Albanian catholicos remained loyal to the Armenian Church, with the exception of a brief schism towards the end of the sixth century. Shortly afterwards Albania was assimilated partly with Armenia and partly with Georgia. There is no mention of any catholicos in Albania after the seventh century. It is asserted by some that the head of the Abyssinian Church, the Abuna, also bears the title of catholicos, but, although this name may have been applied to him by analogy, there is, to our knowledge, no authority for asserting that this title is used by the Abyssinian Church itself.