Systematic reasoning on the Christian faith by the Fathers of the Church. There was scarcely any theology among the early Fathers, Clement of Rome and Ignatius of Antioch, who practically repeated the data of Scripture and the apostolic preaching with a minimum of reasoned analysis. In the second and third centuries, however, contact with the pagan world produced a reaction. Two types of apologists arose, traditionalists, such as Tatian, who rejected philosophy, and others such as Justin, who were willing to use Greek speculation in the interests of the faith. Fortunately for the latter, who were in danger of Gnostic absorption, St. Irenaeus urged the need of remaining faithful to the Church's tradition, the living depository of revealed truth.
The more speculative line of St. Justin was developed by Clement of Alexandria and Origen, with consequent influence on the great Cappadocians, Basil, Gregory of Nyssa, and Gregory of Nazianzus. Characteristics of the Alexandrian school were a marked leaning toward Platonism, an allegorical interpretation of Scripture, and a profound mysticism.
By contrast, the more positive Aristotelian school of Antioch produced St. John Chrysostom, Theodore of Mopsuestia, and Theodoret, who affected the movement of theology through the whole patristic age. The high points of subsequent controversies coincided with the first seven ecumenical councils, which profited from both the Alexandrian and Antiochian schools in defining the principal dogmas on the Trinity and the person of Christ. Among the Fathers no one contributed more to theological growth than St. Augustine. He synthesized the four centuries of tradition which preceded him, clarified and in many cases solved the most vexing dogmatic questions, and co-ordinated the ensemble of sacred knowledge which St. Thomas Aquinas and the Scholastics later organized into a unified system of Christian thought.