Hierarch Theophilus Antioch

St. Theophilus, Bishop of Antioch, was born in Syria in the early 2nd century into a pagan family. Well educated and versed in Greek literature and philosophy, he came to Christianity through independent study of the Old Testament prophetic writings and, convinced of the superiority of Christian teaching, was baptized as an adult. Around 169 AD he was consecrated Bishop of Antioch, becoming — according to the church historian Eusebius of Caesarea — the sixth bishop of that see after the Apostles. He zealously defended the Christian faith, writing several polemical works against heretics (Marcion, Hermogenes) and apologetic treatises answering pagan criticism of Christianity, though only one work survives to this day: To Autolycus (Ad Autolycum), composed shortly after 180 AD. St. Theophilus holds an important place in the history of Christian literature as the first writer known to apply the Greek term "Trinity" (τριάς) to God, describing God, His Word, and His Wisdom as images of the Trinity corresponding to the three days of creation. He reposed not earlier than 180–181 AD. His feast is kept on 13/26 October in the Russian Orthodox calendar.