Calvinists often claim that their theology is not something which arose through the writings of John Calvin and Ulrich Zwingli. To support this thesis, they usually cite St. Augustine, the doctor of grace. Here are five reasons why I do not believe Calvinists are truly Augustinian in their soteriology. Though they can certainly cite him as an influence, the theology of Concord is much closer to that of Augustine and his early predecessors.
1. Augustine saw baptismal regeneration as essential for his soteriology. In some ways, baptism is the foundation of Augustine's theology. Read for example, his treatise On the Forgiveness of Sins and Baptism. His entire defense of original sin was through its remedy in baptism. Within his anti-Pelagian writings, Augustine constantly refers back to baptism as a primary means God uses to give his free grace, and free man's will. There is no immediate operation of the Spirit in Augustine. The Spirit works through word and Sacrament. The Lutheran church from the beginning held to baptism as the means which God uses to give grace and overcome our Adamic state.
2. Augustine denied the "P" of Tulip. In his treatise On the Perseverance of the Saints, Augustine defends the perseverance of the elect, but defends at length that those who are truly regenerated and saved can fall away from the faith. This both Luther and the Lutheran Confessions confessed.
3. Augustine did not believe in limited atonement- at least not in the Calvinistic sense of the term. Yes, there are times when he talks about the particularity of the death of Christ. However, it would not do justice to Augustine to say that he only talked of particular grace. He believed that God gave true grace to non-elect men. His discussions of baptism and the means of grace make it clear that there is universal grace. This is more than mere common grace which only restricts the wicked actions of men and gives some outward blessings men do not deserve. None elect men are truly forgiven through baptism, though they will eventually reject it.
4. The Augustinian definition of double predestination, at least as explained by later writers, is not Calvinistic. Augustine himself did not focus much on the double aspect of predestination and explain what the predestination of the reprobate means. However, the later Augustinian tradition as developed by Prosper of Aquitaine, Fulgentius of Ruspe, and ultimately the Council of Orange, when defining double predestination always made the point that when men are predestined unto death, they are only predestined based upon foreseen future demerits. This goes against not only a supralapsarian view, but also an infralapsarian view which would argue that the reprobate were predestined in view of Adam's sin but not necessarily their own. The Augustinian tradition would thus argue that is man is saved it is unconditional, though if he is damned it is conditional.
5. Augustine started his discussions of predestination from Biblical anthropology and the greatness of God's grace to fallen sinners. Calvinism has often, though not always, discussed predestination under the realm of God's sovereignty. This is secondary for Augustine, and for the Lutheran Confessions.