There is a move among Finnish and Scandinavian theologians in general to draw parallels between the theology of Martin Luther and Maximus the Confessor. While such parallels are interesting, it might be more interesting and necessary to first state the obvious differences.
Maximus and Luther are working with two different notions of salvation and atonement, with Luther more focused on the individual and Maximus on cosmic salvation (see my blog explaining Maximus here). Luther holds to an Augustinian notion of original sin and his theology is slanted if not defined by his focus on forensics.
Is his focus on forensics or on law versus grace definitive of his theology, such that there is no ontological understanding or access to divine essence? One might argue the point, but this is not an uncommon conclusion about his theology, which stands in contrast to Maximus picture of access to the divine essence in creation and incarnation. Is imputed righteousness characteristic of Luther’s theology, such that it all is defined in legal or theoretical terms? Some Lutherans might argue otherwise and this may not be fair to the fulness of his theology, and there are those (such as the Finnish theologians) who argue Luther had his own notion of apocatastasis, but what can be said is that Calvin comes in the wake of Luther and Calvin’s theology is forensic (and Luther’s is commonly perceived as being of a similar order). On the other hand, Maximus follows Origen and the early church in his depiction of theosis (perhaps not entirely absent in Luther) – bringing to maturity in the second Adam the race of the first Adam through divinization. Maximus sees this as a present reality unfolding toward the eschaton.
Luther’s theory of the two kingdoms allows for full participation of the Christian in the necessities of state violence, including the violent suppression of peasants, Jews, and heretics. The peace of Maximus, the enacted theosis in the life of the believer, the cosmic context of virtue grounded in the incarnation of Christ, stands in contrast to Luther’s picture of the Christian life as an unending (violent?) struggle with sin.
Maximus’ picture of salvation is holistic and unified (grounded as it is in the reality of the Trinity) while Luther depicts a split individual struggling with sin, living in two different kingdoms, such that the spiritual and hidden kingdom of God momentarily serves the immediate and practical necessities of the earthly kingdom, allowing this ethic to dictate the lived Christian ethic. Luther affirms the necessity of violence and maintains that people of faith are to be the instruments of violence. After all, “The deviancy of some would call down punishment on all. At a certain point, God even owes it to himself, as it were, to his honour, we might say, to strike.”
Luther tended to demonize his enemies with a violent and abusive rhetoric (which is not to ignore that he often spoke of love), and there is no question that his antisemitism is imbibed by the creators of the Holocaust. Maximus depicts salvation as the destruction of death, and this is the resource and reality out of which the Christian is to live. Monk Maximus would die at the hands of the state and it is not entirely implausible that, given the right circumstance, the ex-Monk Luther might have approved.
But this cursory list of contrasts does not get at the world of difference between Maximus notion that creation is incarnation and Luther’s semi-nominalism. For Luther, God, in his essence is hidden from us, and we do not live with the resource of access to the immanent Trinity. For Maximus, God is revealed in Christ and this is the truth not only of salvation but of the purposes of creation. Luther’s theology lays the groundwork for modernity while Maximus’ theology is the culmination of a premodern theology, pointing toward a very different sort of world order. The enchantment of the world in light of Maximus’ Christo-logic (which is not any old sort of enchantment or magic) and the disenchantment of the world in light of Luther’s direct attack on indulgences and magic, and the secularism implicit in Luther’s thought and theology gets at the fundamental difference. And of course, this is not to attribute (blame/credit) all of secularism to Luther, but again, his theology seems to have enabled secular developments.
As Charles Taylor describes it, Luther reversed the fear factor in his attack on indulgences and on the magic the church could enact (a needed disenchantment):
A great deal of Catholic preaching on sin and repentance was based on the principle that the ordinary person was so insensitive that they had to be terrified into responding. . .. But just this cranking up of fear may have helped to prepare people to respond to Luther’s reversal of the field.
We can locate Luther within the context of nominalism – as nominalism defines both what he is for and what he is against and it is in a nominalist context that he makes these arguments. The father of nominalism, the way of the modern (via moderna), William of Ockham (1287-1347), denied the existence of universals (nominalism indicates we have only the names), which was an underlying foundation for Thomas (1225-1274) and Scotus (1266-1308). Consequently, Ockham would stress the importance of the will (God’s and man’s) over and above the intellect. Luther will challenge the role of human will, attacking what he sees as semi-Pelagianism.
Luther believes that God’s absolute power renders the efficacy of the human will entirely useless. Or in terms of human understanding, it is not as if God can be aligned with the good (as we know it) as God is determinative of the good and so the good must be aligned with the (arbitrary?) will of God.
As Luther states it in the 19th Thesis of the Heidelberg Disputation: “Anyone who observes the invisible things of God, understood through those things that are created, does not deserve to be called a theologian.” God is not grasped through the being of the world (against the scholastics) but God comes to us only on the basis of promise or covenant, and this does not pertain to His essence or the essence of the world. As Taylor puts it, “God must always remain free to determine what is good. The good is whatever God wills; not God must will whatever is (determined by nature as) good. This was the most powerful motive to reject the “realism” of essences for Occam and his followers.”
This sets up a peculiar Lutheran dialectic, in which faith stands over and against reason or in which the theology of glory is opposed to the theology of the cross. The theology of glory clings to works-righteousness while the theology of the cross is dependent on faith alone. Likewise, grace stands over and against law, yet grace needs the law that it might be understood to be a gift and not an accomplishment of the law. If the law “serves no other purpose than to create a thirst and to frighten the heart,” the gospel “satisfies the thirst, makes us cheerful, and revives and consoles the conscience.” The “presumption of righteousness is a huge and a horrible monster. To break and crush it, God needs a large and powerful hammer, that is, the Law, which is the hammer of death, the thunder of hell, and the lightning of divine wrath” (26.310). The greater the paradox, conflict, and struggle, all the better:
“All the works of God are in conflict with His promise, which nevertheless remains completely true and unshaken. . . . The marvelous counsels of God in governing His saints must be learned, and the hearts of the godly must become accustomed to them. When you have a promise of God, it will happen that the more you are loved by God, the more you will have it hidden, delayed, and turned into its opposite” (4.326).
As David Tracy describes it, “Luther’s notion of dialectic … is structured as a conflict of opposites that not only clash but imply and need each other.” The dialectic, like any dialectic refers only to itself, so that what is known pertains not to any necessarily existing reality but to the language of dialectic.
God has his own autonomous purposes which are beyond human comprehension, but what can be known is what God has promised. For Luther, God is the cause of all things, while the human remains a passive recipient of God’s action. There is no free will for man in Luther’s estimation: “We do everything of necessity, and nothing by ‘free-will’; for the power of ‘free-will’ is nil, and it does no good, nor can do, without grace.” According to Roland Millard, for Luther, “The sovereignty of God’s will necessarily excludes any causality on the part of the human person.” Where Maximus describes a synergistic working of human will with the will of God, for Luther human will stands over and against the will of God.
In this understanding, Scripture no longer pertains to ontological necessity but to covenantal promise. Scripture is proclamation and promise so that rather than salvation history or ontological realism, for Luther the Word is a promise. The Word is the means by which God condemns sin and promises salvation (the law and the gospel). But this promise is had, not through the achievement of a real-world defeat of sin, but only on the basis of promise: “Sin is always present, and the godly feel it. But it is ignored and hidden in the sight of God, because Christ the Mediator stands between” (26.133). It is not that sin and the law are ever suspended or surpassed: “There is a time for ‘killing’ the flesh through the law, and a time for reviving the spirit through the gospel. Complacency and self-righteousness require the former, fear and despair the latter. The one ‘who masters the art of exact distinction between the Law and the Gospel should be called a real theologian’ (23.271; cf. 26.115). Though Luther finds the Gospel partly revealed in the Old Testament and he finds the Law mixed in with the New Testament, his primary point is that the Law of the Old Testament stands over and against the Gospel of the New Testament.
Maximus notion of free will, his picture of the whole Bible and the whole world proclaiming the Gospel seems contrary to Luther’s sharp divide between Law and Gospel and between creation and Creator. Whether one agrees with the cosmic (universal) salvation of Maximus and his peculiar Christo-logic, or whether one prefers Luther’s faith alone and imputed righteousness, it would be a mistake to blend these two contrasting worlds without noting their stark difference. The two contrasting orders of salvation, revelation, and the God/world relation in Maximus and Luther represent two very different conceptions of Christianity and the world.
 Charles Taylor, A Secular Age (Harvard University Press, 2007) 42. An understanding Taylor links to Luther.
 By the same token, we might sight the history of modern Western philosophy as in some sense flowing from within the wake of Lutheranism. Is the dualism of Descartes (between faith and reason), or Kant’s split between the noumena and the phenomena (and the eventual turn to phenomenology), far removed from Luther’s two kingdoms and his interiorized Christianity? In fact, faith alone (sola fide) does not seem too far removed from German idealism. Luther’s focus on a groundless Word (not grounded in metaphysics) will come to resemble phenomenology and the linguistic turn in philosophy and society. While it is too simplistic to chalk this up to Luther, it is doubtful it could have happened apart from the Reformation instigated by Luther.
 At least this is the argument of Charles Taylor.
 Taylor, 75.
 Roland Millare, “The Nominalist Justification for Luther’s Sacramental Theology” (Antiphon 17.2 (2013)) 169-170.
 Taylor, 97.
 Luther’s Works Volume 23, p. 272 hereafter cited by volume and page.
 Stephen and Martin Westerholm, Reading Sacred Scripture: Voices from the History of Biblical Interpretation (p. 233). Wm. B. Eerdmans Publishing Co.. Kindle Edition.
 D. Tracy, ‘Martin Luther’s Deus Theologicus’ in P. J. Malysz and D. R. Nelson, eds, Luther Refracted (Minneapolis: Augsburg, 2015): 109. Quoted in Mark Norman, “Luther, Heidegger and the Hiddenness of God” Tyndale Bulletin 70.2 (2019) 302.
 Luther, Bondage of the Will, 180.
 Millare, 172
 Westerholms, 234.