|Mar Abba the Great|
|Honored in||Roman Catholicism Assyrian Church of the East Chaldean Catholic Church|
|Major shrine||The Seminary of Mar Abba the Great El Cajon, California, United States|
Aba I (or, with his Syriac honorific, Mar Aba I) or Mar Abba the Great was the Patriarch of the Church of the East at Seleucia-Ctesiphon from 540 to 552. He introduced to the church the anaphoras of Theodore of Mopsuestia and Nestorius beside the more ancient liturgical rite of Addai and Mari. Though his tenure as catholicos saw Christians in the region threatened during the Persian-Roman wars and attempts by both Sassanid Persian and Byzantine rulers to interfere with the governance of the church, his reign is reckoned a period of consolidation, and a synod he held in 544 as instrumental in unifying and strengthening the church. He is thought to have written and translated a number of religious works.
Aba is a highly regarded and significantly venerated saint in the Assyrian Church of the East and the Chaldean Catholic Church, which has a seminary in San Diego, California, USA, is named after him. His feast day is celebrated on both the seventh Friday after Epiphany and on February 28.
 Early life
Born in a Zoroastrian family in Hala, Mesopotamia, Mar Aba was secretary to the governor of Beth Garmai province before he converted to Christianity, studied, and later taught at the School of Nisibis. Highly regarded as a scholar, he studied Greek in Edessa and is attributed with the translation (or with having overseen the translation) of key texts, including the works of Theodore and Nestorius, from Greek into Syriac. He is also remembered as the author of original works including Biblical commentaries, homilies, and synodal letters.
 Commentaries of Theodore
He favoured the Biblical interpretation and commentaries of Theodore of Mopsuestia, at the time a controversial position: the Byzantine emperor Justinian attempted to meet with Mar Aba around 532 (before his installation as patriarch) to persuade him to denounce Theodore's teachings. Justinian was preparing to anathematize Theodore and his works, obviously in sharp opposition to Mar Aba's own views. Acquiescence to Justinian's demands would also have been politically undesirable for Mar Aba, whose Church of the East had secured independence from the Christian west (which Justinian represented) at the Council of Dadisho in 424; Mar Aba avoided the meeting.
 544 Synod
Aba's tenure as catholicos followed a 15-year period of schism within the church, during which remote areas had elected their own rival bishops. Aba was able to resolve this schism, visiting the disputed areas and negotiating agreements to reunite the church. In 544 he convened a synod to ratify these agreements; the synod agreed that the metropolitans of those regions under the See of Seleucia-Ctesiphon would in future elect catholicoi at a formal meeting. This agreement was, however, substantially subverted in later years, not least when the Persian ruler Khosrau I influenced the selection of Joseph, Aba's successor as catholicos.
The acts of the synod also documented an "orthodoxy of faith", written by Aba himself. Some of its prescriptions indicate the particularly Persian character of the church in the East, including a set of marriage rules prohibiting unions between close kin, apparently formulated in deliberate response to Zoroastrian practice. Finally, the synod ratified the canons and decrees of the Council of Chalcedon, held around a century earlier, which included proclamations on the divine and human nature of Christ and a number of disciplinary rules for the clergy.
 Tensions with Persia and Rome
Tensions between the Persian and Byzantine empires ran high during Mar Aba's lifetime, and after hostilities between the two intensified in the 540s the persecution of Christians in Persia also became more common. Zoroastrians hostile to Aba as an apostate pressured Khosrau to act against him, and as punishment for proselytizing among the Zoroastrians Aba was placed under house arrest, and later exiled to Azerbaijan. He was allowed to return to the See after seven years and continued as Catholicos until 552, when he died — in some accounts, as a result of torture and exposure inflicted during his imprisonment.
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|Catholicus-Patriarch of the East