Saint Flavian of Antioch was a prominent Christian bishop in the 5th century, known for his leadership in the early Church. He served as the Patriarch of Antioch and played a significant role in the theological debates of his time, particularly concerning the nature of Christ. His tenure was marked by opposition to the teachings of Nestorius, which emphasized the duality of Christ's nature. Flavian is remembered for his commitment to the Council of Chalcedon in 451 AD, which affirmed the doctrine of the two natures of Christ—divine and human. His efforts to uphold orthodox Christian beliefs led to conflicts with various factions, ultimately resulting in his exile and martyrdom.