Certain leaders of great prominence in the second century are called distinctively Church Fathers. Irenæus, the Bishop of Lyons in Gaul, was a theologian who centered his writings on the relationship of the Son to the Father. He also wrote about salvation, the importance of baptism, and the need to follow the apostolic tradition. Tertullian of Carthage was educated for the law and he used legal language in his theological definitions. He introduced certain words into theological vocabularies, like “substance” and “merit.” He brought the word “Trinity” into theological use and made the personality of the Holy Spirit distinct. He distinguished the two natures in Christ in a way that foreshadowed the later thinking of the Greek Fathers.
Impact: The Church Fathers anticipated Augustine by two centuries in their formulation of the doctrine of original sin and in their acceptance of the principle of divine grace.