He was an opponent of the Pelagians, which helped increase his popularity among the citizens of Constantinople, and he contributed to the theological framework for the developing cult of the Virgin Mary.

Born at Sivas in the second half of the 4th century, Atticus early embraced a monastic life and received his education from Macedonian monks, a fact which restricted his philosophical learning and ensured he would always have an Armenian accent considered unpleasant to Greek ears.

[1]: 26  The expulsion of Chrysostom took place 10 June 404 and his successor, the aged Arsacius of Tarsus who was the brother of Chrystom's predecessor Nectarius of Constantinople, died 5 November 405.

[4] Vigorous measures were at once adopted by Atticus in conjunction with the other members of the triumvirate to which the Eastern church had been subjected, Theophilus I of Alexandria, and Porphyry of Antioch, to crush the adherents of Chrysostom.

A large number of the bishops of the East persevered in the refusal, and suffered a cruel persecution; while even the inferior clergy and laity were compelled to keep themselves in concealment or to flee the country.

The small minority of Eastern bishops who for peace's sake deserted Chrysostom's cause were made to feel the guilt of having once supported it, being compelled to leave their sees and take other dioceses in the inhospitable regions of Thrace, where they might be more under Atticus's eye and hand.

A large proportion of the Christian population of Constantinople still supported their former bishop, with many refusing communion with the man they considered a usurper and continuing to hold their religious assemblies, more numerously attended than the churches, in the open air in the suburbs of the city.

Persian and Syrian influence was growing in the Armenian Church during this time, and Bishop Atticus had to navigate a diplomatically sensitive affair.

A treatise On Faith and Virginity, combating by anticipation the errors of Nestorius, addressed to Roman emperor Theodosius I's daughters Pulcheria and her sisters, is mentioned by Marcellinus Comes.

Constas identifies this strong Christological-Mariological synthesis in the intellectual and devotional climate of the city, building upon earlier works by figures like the Cappadocians, as the catalyst for later Nestorian repudiation.

Because of his reputation for devotion to Mary, it is probable that the first official Marian feast in Constantinople, held during the Nativity cycle, was introduced during Atticus' tenure.