(born 4th century, Germanicia, Syria Euphratensis, Asia Minordied c. 451, Panopolis, Egypt) Founder of Nestorian Christianity. Born of Persian parents, he studied in Antioch and was ordained a priest. As bishop of Constantinople from 428, he aroused controversy when he objected to Cyril of Alexandria's granting Mary the title of Theotokos (God-Bearer), which he believed compromised Christ's full humanity. In 431 the Council of Ephesus condemned his teaching as heresy on the ground that he denied the reality of Christ's incarnation, and Nestorius went into exile, first in the Libyan desert and then in Upper Egypt. Nestorianism was adopted by the Persian church, whose members still adhere to his ideas.