The Fathers of the Church were all theologians, and some were even bishops. They wrote extensive treatises or treatments in theology especially centering on the divinity and humanity of Jesus Christ. In the first few centuries of the Church there was much confusion, and the Church Fathers wrote to curtail heresy and spread orthodoxy, which is Greek for correct thinking.
The deposit of faith had been taught to the apostles by Jesus Christ, and then by the Holy Spirit, after the Ascension ended with the last apostle, Saint John. After his death, no new public revelation was given. The work of Church Fathers and ecumenical councils in the promulgation of doctrine from the Chair of Saint Peter provide further explanations to the already believed and revealed truths.
Church Fathers lived exemplary lives and were often canonized saints. They lived during the time of the early church up until the ninth century. Church Fathers include, from the West, Saint Ambrose, Saint Augustine, Saint Jerome, Pope Saint Gregory the Great, Origen, and Tertullian; from the East, Saint Basil, Saint John Chrysostom, Saint Gregory Nanzianzen, and Saint Athanasius.
Saint Athanasius lived during the time of the Arian heresy, which divided the Church. His major work was in defending the fact that Jesus, the Second Person of the Blessed Trinity, was equal to the Father. Saint Gregory of Nazianzus wrote “Theological Discourses,” while Saint Gregory of Nyssa was an important figure at the Ecumenical Council of Constantinople. He wrote on the origin and creation of man. Saint John Chrysostom, who was born in Antioch, was a great preacher.
Eventually he became the bishop of Constantinople. He wrote many commentaries on Scripture and different theological works on the priesthood, matrimony, and the vows of virginity. Saint Jerome is credited for translating the first complete one volume Bible (400 AD) into Latin from the original Hebrew and Greek texts.