Martin Luther famously critiqued and rejected Aristotle, and the impact that Aristotelian philosophy had had upon Christian theology in the late medieval period; particularly as mediated through the synthesis of Thomas Aquinas’s theology with Aristotelian philosophy. This was such a fundamental piece for Luther, that it can be said, as Alister McGrath, and my former seminary professor and personal mentor, Ron Frost have said, that this rejection and repudiation of Aristotle’s impact on Christian theology led, theologically, to Luther’s “breakthrough” in regard to his understanding of sola fide, and the material principle of the Protestant Reformation theology. The implication of this, if followed, is that theological reasoning is strictly reduced to reliance upon the revelation of God in Christ apprehended by faith.
As McGrath sharpens this further, he underscores why this move for Luther was so important; he underscores why working away from Aristotelian and forensic conceptions of God’s righteousness, and working from the righteousness of God revealed by Christ is so important and so delimiting for a genuinely Christian approach to the theological task. McGrath writes:
For Luther, ratio and its associated concept of iustitia (as used by Aristotle and the jurists) had its proper place in the ordering of civil affairs. Luther’s rejection of ratio relates to his soteriology, particularly to the definition of iustitia Dei, which is of central importance to his theology as a whole. The concept of iustitia which Luther rejected in this context is none other than that of Aristotle’s Ethics, which had been taken up by the medieval canonists and jurists, which had found its way into the soteriology of the via moderna, and which corresponded to a secular, commen-sense understanding of justice in terms of a quid pro quo morality, whose validity was immediately apparent to reason. Julian of Eclanum had insisted that God judged man rationabiliter, which he took to be equivalent to iuste, and had therefore applied to a common-sense concept of iustitia by a process of analogical predication to God. God rewards each man according to his merit, which may be defined in terms of whether he has lived well by the standards set him in the law: non ego, sed ratio concludit. A similar interpretation of iustitia Dei can be derived by direct analogical predication of the Aristotelian understanding of iustitia, linked with the associated interpretation of the relationship between iustitia and lex, to God. The young Luther appears to have adopted precisely such a concept of iustitia in his early attempt to expound the Psalter: indeed it is of particular significance that Luther should choose Psalm 9 (10). 9 to expound the relationship between iustitia and equitas in the divine judgement, as Julian of Eclanum had earlier used exactly the same passage to demonstrate the divine equity in dealing with man according to his merit! It was against this understanding of iustitia, as applied to God (but not applied to civil affairs), that Luther rebelled when he discovered the mira et nova diffinitio iustitiae, with such momentous results for his theology. Luther’s revolt against reason is indeed occasioned by his soteriology — but in a far more specific manner than appears to have been generally realised. Whilst it cannot be proved that Luther appreciated the theological ramifications of everything he read in Book V of the Nichomachean Ethics, it is beyond dispute that he recognised that the concept of iustitia developed therein, applied to God, had appalling theological consequences for sinners: Tota fere Aristotelis Ethica pessima est gratiae inimica. Luther’s joy at his discovery of the new definition of iustitia reflects his realisation that God loves and forgives sinners, and that the iustitia of iustitia Dei is not to be understood qua philosophi et iuriste accipiunt, but qua in scriptura accipitur. Luther’s vitriolic attacks against Aristotle, reason, the jurists, the law, and the Sautheologen of the via moderna reflects his basic conviction that all these employed a concept of iustitia which, when applied to God, destroyed the gospel message of the free forgiveness of sinners. Luther’s ‘evangelical irrationalism’ is closely correlated with his discovery of the righteousness of God: if reason and its allies were unable to comprehend the mystery of the justification of the ungodly, then so much the worse for them. Reason has its role to play in the civil affairs of men, as in so many other spheres — but when faced with the justification of sinners, the central feature of the gospel proclamation, it collapses, unable to comprehend the mystery with which it is confronted. For Luther, the word of the gospel, upon which all theological speculation was ultimately based, was that of a righteous God who justified those worthy of death: if reason was unable to comprehend this fundamental aspect of the gospel, it had forfeited its right to have any say in theology as a whole. In Luther’s opinion, reason was not neutral in this matter: according to reason, God should only justify those whose deeds made them worthy of such a reward: itaque caro est ipsa iustitia, sapientia carnis ac cogitatio rationis, quae per legem vult iustificari. Human wisdom and human concepts of righteousness are inextricably linked — and, as Luther emphasised, both were called into question by the fact that a righteous God could justify sinners. It is clear that this critique of human wisdom, which is ultimately based upon Luther’s deliberations upon the concept of the ‘righteousness of God’, foreshadows the theologia crucis of 1518 in a number of respects. Before moving on to consider the nature of the theology of the cross, however, it may be helpful to summarise our conclusions concerning the nature and the date of Luther’s theological breakthrough.
It is precisely for what McGrath just detailed that Ron Frost in 1997 wrote an essay for the Trinity Journal entitled: ‘Aristotle’s Ethics: The Real Reason for Luther’s Reformation?’ Frost believes, and I agree with him, that insofar as the following Post Reformation Reformed orthodox theology imbibes a ‘Christian Aristotelianism’ it has skipped off the central critique of Luther’s protest movement; which is very ironic indeed. Note Frost’s analysis here:
An alternative paradigm, advocated here, is that Luther’s greatest concern in his early reforming work was to rid the church of central Aristotelian assumptions that were transmitted through Thomistic theology. To the degree that Luther failed—measured by the modern appreciation for these Thomistic solutions in some Protestant circles—a primary thrust of the Reformation was stillborn. The continued use of Aristotle’s works by Protestant universities during and after the Reformation promoted such a miscarriage. Despite claims to the contrary by modern proponents of an Aristotelian Christianity, Aristotle’s works offered much more than a benign academic methodology; instead, as we will see below, his crucial definitions in ethics and anthropology shaped the thinking of young theological students in the sixteenth and seventeenth centuries who read the Bible and theology through the optic of his definitions. Luther recognized that Aristotle’s influence entered Christian thought through the philosopher’s pervasive presence in the curricula of all European universities. In his scathing treatise of 1520, To the Christian Nobility of the German Nation, Luther—who for his first year at Wittenberg (1508-9) lectured on Aristotle’s Nicomachean Ethics four times a week—chided educators for creating an environment “where little is taught of the Holy Scriptures and Christian faith, and where only the blind, heathen teacher Aristotle rules far more than Christ.”
This is quite profound, to say the least! It is this very premise and insight as developed by Ron Frost, and illustrated by the work of McGrath, that has led me to my form of evangelical Calvinism. It is this fundamental critique and insight that not a single contemporary Reformed thinker or theologian I have come across has grasped whatsoever. I know many who read me seem to think that evangelical Calvinism, my form, is wholly contingent upon Barth and Torrance, but that is way too quick and limited of a conclusion to draw!
It is ironic, indeed, that the most adamant of Reformed voices today simply and uncritically accept the research of someone like Richard Muller who advocate for the Post Reformed orthodox re-appropriation of a ‘Christian Aristotelian’ mode; this is ironic because the very thing that kicked off the Protestant Reformation was in protest to Aristotle’s influence on Christian theology; particularly the impact that played on defining God’s righteousness and how that implicates a variety of things; including how ‘faith’ is conceived. If someone wants to critique evangelical Calvinism, at least my form, then start with engaging with Luther’s critique of ‘Christian Aristotelianism,’ the informing “theology” of what now constitutes most of Reformed theology, proper.
 Alister E. McGrath, Luther’s Theology of the Cross (Oxford: Basil Blackwell, 1985), 139-41.
 R.N. Frost, “Aristotle’s “Ethics:” The “Real” Reason for Luther’s Reformation?,” Trinity Journal (18:2) 1997, p. 224-25.