Righteous Theophilus of Antioch

Saint Theophilus of Antioch was an early Christian apologist and bishop of the 2nd century, the sixth bishop of Antioch after the apostles. Born into a pagan family in Syria in the early second century, he received a thorough Greek education, converting to Christianity after reading the Old Testament prophetic books. Around 169 he became bishop of Antioch and zealously defended the Christian faith against heresies such as Gnosticism and Marcionism, as well as pagan attacks. Of his many writings — against heresies, commentaries on the Gospel, historical works — only one survives: the three-book treatise "To Autolycus," an apology of Christianity addressed to an educated pagan. In this work he was the first Christian writer to use the term "Trinity" for God, His Word, and His Wisdom. He died around 183–185, under Emperor Commodus.