Early Career and Defense of Nicene Orthodoxy
Around 360–361 Flavian was ordained to the priesthood by Meletius of Antioch. Working alongside Diodore of Tarsus, he defended Nicene Christianity against Arianism during the episcopate of the Arian bishop Leontius of Antioch.
According to Theodoret, it was in the meetings led by Flavian and Diodore — assembled outside the city walls — that the practice of antiphonal singing was first introduced into the services of the Church.
Succession and the Meletian Schism
When Meletius of Antioch died in 381 during the First Council of Constantinople, at which Flavian participated, Flavian was chosen to succeed him as bishop of Antioch. He inherited a complicated and long-standing division in the see.
A rival faction, the Eustathians, maintained a separate patriarchal authority — led first by Paulinus II and, after 388, by Evagrius — with the support of Rome and Alexandria. When Evagrius died around 392–393, Flavian prevented the election of a replacement, though the schismatic faction continued its separate worship.
Through the intervention of John Chrysostom after his elevation to the Patriarchate of Constantinople in 398, and with the influence of Emperor Theodosius I, Flavian was acknowledged in 399 as the sole legitimate Patriarch of Antioch, reconciled with the sees of Alexandria and Rome. The schism itself was not fully healed until 415, under Alexander of Antioch, more than a decade after Flavian's death.
Intercession for Antioch
When the citizens of Antioch angered the emperor by destroying his statue, Saint Flavian sought to obtain from the Emperor Theodosius (379–395) a pardon for the city.
By the account of the synaxarion, his death was peaceful and without illness.