Protestants of a certain stripe are all about retrieving classical theologies, particularly of a Thomistic hue. These Protestants typically, and rightly, as the case may be, start by retrieving theology proper (doctrine of God) categories, and then work their way from there. They terminate in soteriology; and in the Protestant frame I’m thinking of, this termination looks most closely akin to Federal (Covenantal) theology. Built into Federal theology is a notion of bi-lateral contract between God and humanity. God provides the grace and salvation, and the elect person (if they don’t have a temporary faith) co-operates with that grace thus meeting the conditions required for acquiring final justification (aka ‘glorification’).
Lutheran theologian, and ethicist, Helmut Thielicke describes this theory of salvation in the following way. You will notice that his sketch is in discussion with the Augsburg Confession which stands in contraposition to the Catholic (and Thomistic) understanding of salvation. If you are familiar with Lutheran (and Reformed theology) you will immediately pick up on the Law/Gospel combine Thielicke and the Augsburg Confession are thinking through.
What happens when particular emphasis is laid on the imperative? The Apology draws attention to this problem in a polemical section of Article IV on “Love and the Keeping of the Law.” According to the Thomistic doctrine of justification the imperative, although not exactly isolated and absolutized, is nonetheless accorded an autonomous significance. For justification is linked with the “keeping of the Law,” and the imperative, i.e., the requirement of good and meritorious works, has the significance of co-operation in the attainment of justification. The Apology finds the reason for this primacy of the imperative, or at least for the high degree of emphasis laid upon it, in the Thomistic concept of prima gratia.
In opposition to this accentuating of “initial grace,” the Apology maintains that Christ does not cease to be the mediator after we are renewed. “All those err who maintain that he [Christ] has merited for us only the ‘initial grace’ and that we then subsequently attain acceptance and ear for ourselves eternal life by our keeping of the Law. Christ remains the mediator, and we must always maintain that on his account we have a reconciled God, even though we ourselves be unworthy.
By way of interpretation, it should be noted that the expression “Christ remains the mediator” is an exaggerated formulation which is to be taken with a grain of salt. For it goes without saying, as the Apology realizes well enough, that Thomism does not present the doctrine of justification in such crude and deistic fashion that Christ is, as it were, only the initiator of justification, and that then, having started the movement, he withdraws, after the manner of Deism, and leaves everything to the human action thus “cranked up” and released. Thomism cannot mean this, since it regards all the “merits” attained by man as merits only through grace, and hence only for the sake of Jesus Christ. Hence we must not allow this polemical formulation to give us too simple a view of Thomism.
Nevertheless, the Apology does use this polemical formulation; and if we cannot think that it is simply caricaturing its opponents in order to ease the task of refuting them, we must interpret it as follows. The concept of prima gratia involves a decisive infringement upon and restriction of the mediatorial significance of Christ. For when justification is linked with the prima gratia, this initial grace is regarded as the basis which makes possible our doing of the meritorious works necessary for salvation. Thus grace becomes merely the basis which makes possible the real thing. The real thing is the meritorious works; they are the key to the process of justification. For it is by works that we see whether the grace lent to us is actualized and put to good use, or whether it remains instead idle capital. In the strict sense, therefore, initiatory grace is really the basis of the possibility, the indispensable condition of the real event. In relation to the merits which are normative for salvation, justification has liberating and creative power. Its position is rather like that of a means to an end.
In thus characterizing Thomistic faith as a “means to an end,” we should not forget, of course, that this is an exaggerated formulation because in Thomism grace is in some sense final as well as primary. For what man merits is grace in its quality as an end, as ultimate “goal.” Between the two, however, merits have a decisive position, since they can challenge and even block the way from primary grace to ultimate grace.
In Rome’s assigning of a key position to works, the Apology sees not only an infringement upon the exclusiveness of Jesus Christ, but also a threatened perpetuation of the assaults of doubt [Anfechtung] which Luther sought to overcome. “If those who are regenerated are supposed later to believe that they will be accepted because they have kept the law, how can our conscience be sure that it pleases God, since we never satisfy the law?” If good works occupy the key process of justification, then the assurance of our being accepted and justified by God (the “sure conscience” [conscientia certa]) is continually threatened. For this assurance depends in turn on the assurance that we have fully kept the Law, an assurance that can never be definitive and unequivocal. To the degree that the decisive phase in the process of justification passes into the hands of men, there is always instability, and hence assaults of doubt.
This, in a nutshell, is the stuff that Federal theology is made of. While it is all vouchsafed by the absolutum decretum, and God’s brute sovereignty therein, this is how the Divine pactum unfolds, in a loose way, in Federal theology. Is this by mistake, or is there a correlation between the doctrine of God and soteriology present in the Thomist (Aristotelian) frame? There is a correlation. In other words, the way a theological system thinks God, so goes the rest of its subsequent theologizing. If a system gets a doctrine of God wrong, everything following will be eschewed in orientation to the wrongness of who and what God is conceived to be.
In Evangelical Calvinism, even more expressly than we find in Thielicke’s Lutheran frame, the object of salvation is the subject. In other words, there is no discussion that takes place, about salvation (or anything else!), in abstraction from the concrete life of God in Jesus Christ. Both the person and work of Jesus Christ are thought together, never apart. As such, the ‘imperative’ (Law) of the Christian life is never thought in rupture from its indicative (Gospel), but only together. This is because, for the Evangelical Calvinist, as Thomas Torrance would emphasize, salvation is Grace all the way down; insofar that salvation is God become human in Christ for us (pro nobis). This means, simply, that insofar that the person is in union with the vicarious humanity of Jesus Christ, that this person is justified, sanctified, and glorified, from head to toe, in the robe of Christ’s righteousness. Further, this means that the ‘eternal indicative’ is also the eternal imperative insofar that God freely elected to step into the gap between Himself and fallen humanity. As He stepped into this gap, which is Grace, all conditions, particular to the actualization of re-conciliation between God and humanity, were immediately realized. In other words, the dilemma that Thielicke and the Augsburg Confession are addressing, in regard to the Thomist categories, are never raised as real dilemmas.
For the Evangelical Calvinist there is no sunlight between God’s inner life for us and the human conscience and concrete lived existence we inhabit on a day-to-day basis. And all of this is because the Evangelical Calvinist does not think God from the speculative and Aristotelian categories that Thomism, and her Calvinist (and Lutheran orthodox) iterations do. We think concretely from the evangelical life of God for us revealed and exegeted in Jesus Christ. In other words, we think of God in relational and personalist ways which avoid thinking of Him in terms that are law-like, decretal, and juridical. As such, the dilemma Thielicke is rightly countering, as presented by the Thomist categories, are non-starters for the Evangelical Calvinist. Nevertheless, it is important to understand, contextually, why Evangelical Calvinism offers a positive way forward that does not fall prey to these sorts of dilemmas as given rise by speculative theologies like we find under the umbrella of the Thomisms.
 Thomas Aquinas’ theology, and its subsequent “neo-Thomist” receptions and developments.
 We get ‘poser’ versions of this in sub-set forms in lower iterations of Reformed or more accurately “Calvinist” theologies (think of Five-Point Calvinism, and other like versions; whether those be in direct correlation with, or in contraposition to Five-Pointism).
 See Myk Habets and Bobby Grow, “Theologia Reformata et Semper Reformanda: Towards an Evangelical Calvinism,” in Editors Myk Habets and Bobby Grow, Evangelical Calvinism: Volume 1: Essays Resourcing the Continuing Reformation of the Church (Eugene, OR: Pickwick Publications, 2012), 1-19. Also see Bobby Grow, “Assurance is of the Essence of Saving Faith: Calvin, Barth, Torrance, and the ‘Faith of Christ,'” in Editors Myk Habets and Bobby Grow, Evangelical Calvinism: Volume 2: Dogmatics and Devotion (Eugene, OR: Pickwick Publications, 2017), 30-57.
 Helmut Thielicke, Theological Ethics: Volume 1: Foundations, edited by William H. Lazarus (Philadelphia: Fortess Press, 1966), 74-6.