There is a lot of talk these days in certain (Baptist) sectors about retrieving the theology of Thomas Aquinas. The focus of discussion is typically on his Prima Pars—of his Summa Theologiae—and less on the full scope of Thomas’ theology. But what in fact is being retrieved, if in fact the ultimate desire is to recover Aquinas’ theology in a total way? What about Thomas’ theological anthropology, and as corollary, doctrine of sin; are these foci fulgently available for the Protestants to recover as well? If we look back into the 16th and 17th centuries of what is called the Post Reformed Orthodox development of Reformed (or Calvinist) theology what we find is an affirmative in regard to recovering more than just a doctrine of God from Thomas Aquinas. And so, Thomas’ theology, at least if we move beyond the 21st century Baptists, with an eye towards the Post Reformed Orthodox theologians (like William Perkins et al.), is indeed intent on bringing many of Thomas’ theological themes into the development of their own respective projects as Federally Protestant theologians. In order to gain a better understanding on Thomas’ (and Anselm’s, as the case may be) doctrine of sin let us turn to RN Frost’s treatment of that in his book Richard Sibbes: God’s Spreading Goodness. Frost writes (at length):
Aquinas on privative sin
The first major proponent of privative sin in the medieval period is Anselm whose pioneering work was followed and developed by Aquinas. In a matter crucial to the development of the nomist tradition, Anselm based his doctrine on Augustine’s early doctrine of privatio rather than his post-Pelagian view. The implication picked up by Pelagius—that salvation requires a free act of the volition in choosing God—was assimilated roughly a century later by Aquinas.
Aquinas, as a student of Augustine, was apparently alert to Augustine’s shift on the issue of privatio: he attributed privatio to Anselm and a positive definition (sin as habitus) to Augustine. Aquinas, in fact, sought to synthesize the views of Augustine and Anselm through an analogy much like Augustine’s lost-food solution: “As in a bodily illness there is privation, in that the balance of health is upset, yet also something positive, the disturbed bodily humours, so also in original sin there is privation [privatione], the lack of original justice, yet along with this there are the disturbed powers of the soul.” In this explanation, however, he failed to adopt Augustine’s solution that grace is God’s presence in the elect by the Spirit. This followed Aquinas’s premise that human nature and divine being are wholly incommensurate—a topic taken up in the next chapter. Significantly, Aquinas believed that Adam’s original state of righteousness was not something natural to his humanity but a gift of supernatural grace (donum gratiæ):
Original righteousness [justitia originalis] was a definite gift of grace [donum gratiæ] divinely bestowed upon all human nature in the first parent, which, indeed, the first parent lost in the first sin. Hence even as that original righteousness would have been transmitted along with human nature to the offspring of the first parents, so the opposite disorder is in fact transmitted.”
Thus, subsequent sin in humanity resulted from an incapacity, the loss of Adam’s original righteousness that the donum gratiæ had maintained. Adam had squandered humanity’s golden opportunity by failing to guard his original righteousness.
Aquinas, in these discussions, located privatio within nature, viewing sin as the loss of a created quality. The symmetrical cure for sin, with sin defined as a privatio gratiæ, is a resupply of grace. To this end, Aquinas held that grace has dual aspects, one created and the other uncreated. This doublet allowed him to resolve the tension between original sin and actual sin. When Adam fell he lost the created grace of original righteousness. The implicit ground for his fall was an absence of uncreated grace that was needed because of his human mutability.
This two-stage arrangement assumed that morality is defined by the use of a free will to choose either good or evil. Thus it was God’s purpose to generate a vulnerability in Adam in order to test and affirm his morality. His failure was then transmitted to his progeny by the absence of original righteousness. Privatio, in this arrangement, was twofold: a lack of uncreated grace that led to, but did not compel, Adam’s fall; and a subsequent lack of created grace after the fall due to Adam’s loss of original righteousness. Adam was therefore culpable because of his own initiative in the fall. After the fall Adam’s progeny now lack the grace, both created and uncreated, necessary for righteousness. We are therefore helpless and God’s twin resources of grace are needed for salvation.
Among the Puritans these were points of conversation. Perkins adopted the Thomistic solution with its reliance on a duality of grace. He believed it offered the most coherent solution to the problem of sin when sin is defined as privatio. Sibbes, however, came to see sin as self-love even though he first held Perkins’ view. And with that he also took up Augustine’s view of grace as God’s relational bond to the elect.
We can see the way Frost is arguing in regard to making a distinction between two Puritans, William Perkins and Richard Sibbes, respectively. For our purposes what stands out in this treatment is the development of Aquinas’ doctrine of sin (and grace), as Frost identifies an Anselmian (and Aristotelian, not explicitly referenced in this context) background to said doctrine. What is significant, to my mind, is how Aquinas, if Frost’s treatment is accurate, thought of grace to begin with. What was needed, in his frame, for salvation to obtain in an individual person, was created grace. But this notion, even while funded by the broader reality of an ‘uncreated’ grace, was thought of in qualitative or substantial terms. And so we end up with a necessary separation between the work of God in salvation, and the person of God. This occurs, in the Thomist sense, insofar that grace is not in fact the act of God’s person for the world in Jesus Christ. And that the person of Christ by the Spirit is not understood, then, as the basis of what grace is in itself (ontologically). So grace becomes, in a Thomist sense, something that the elect must manage or cooperate with in order to appropriate God’s salvation for them. And it can become a ‘thing’ that is dispensed through the Catholic mass, as the Eucharistic body is given to the faithful. Frost will argue that the Federal theology of someone like William Perkins retrieved this Thomist frame for thinking grace, and built it into his own style of Federal (Covenantal) theology. That this frame, indeed, funds the theology of the Westminster Confession of Faith in general.
But there is a better way to think grace, even as that is understood in an Augustinian key (as Frost also argues). Personally, I think the best way to think grace in a relational frame is to do so in an Athanasian key; that is, to think it as distinctively relational and personal. What is interesting about Frost’s work is that he develops that possibility from Augustine himself. TF Torrance believes that Augustine is guilty of what TFT calls the ‘Latin Heresy.’ That is a type of nascent dualism as Augustine thinks the work of God vis-à-vis the person of God. But this might be too hasty of a characterization by TFT. If Frost is right about Augustine, in regard to his relational and ‘affective’ understanding of grace, then what we have in Augustine, while still neo-Platonic (thus TF’s charge that Augustine is engaging in the ‘Latin heresy’), is the very type of personalist and ontological understanding of grace that TFT attributes exclusively to Athanasius (and the Nicene trad). In other words, maybe there was more availability in Augustine’s theology, in regard to an ontological and relational understanding of grace, than TFT gave Augustine credit for. Based on Frost’s work it would appear, in certain ways, that TFT may have been reading Augustine through the Thomist and Westminster reception rather than reading Augustine himself. If so, this would open the door for an Evangelical Calvinism to have a good basis for working not just with Athanasian themes, but also with Augustinian ones as well. An Evangelical Calvinism is more concerned with recovering the ‘reverend teaching’ than it is with the genealogy of said teaching, per se.
Either way, Thomas’ doctrine of sin, based on an Anselmian theme, is not commensurate with an Evangelical Calvinism. And so, we must continue to eschew a Thomism, a Federal or Westminster Calvinism, a classical Arminianism so on and so forth. Evangelical Calvinists are focused, along with Frost’s Augustine, with understanding God from God as immediately Self-revealed by the Holy Spirit in Jesus Christ. An Evangelical Calvinist thus cannot endorse a Thomist doctrine of sin, nor any other receptions of that as that is developed in juridical and commercial ways as primarily observed in the theology of the Post Reformed Orthodox Protestants.
 RN Frost, Richard Sibbes: God’s Spreading Goodness (Vancouver, WA: Cor Deo Press, 2012), 124-26 (based on Frost’s PhD dissertation written at King’s College, University of London, 1996).