Edward Feser (paraphrasing Michael Allen Gillespie):
Renaissance humanism represents the attempt to make sense of the world post-Ockham by privileging the human realm over the divine and natural realms. The anxiety over the human condition that results from the frightful nominalist-cum-voluntarist conception of God was countered by an appropriately nominalist and voluntarist understanding of man as a self-creating individual whose quasi-divine dignity sets him above the rest of the natural world.
The Protestant Reformation, in turn, would emphasize the divine realm over the human and the natural. The latter realms could not fail to be subordinate to the terrifying God of nominalism, overwhelming in His power and inscrutable in His will. This same God was, however, the source of Luther's spiritual anxiety. Since such a God might damn one no matter what good works one performed, assurance of salvation could be found in faith alone. This put the Reformation on a collision course with the humanists, whose emphasis on man's self-mastery was seen as Pelagian and whose commitment to free will was regarded as incompatible with divine omnipotence. Hence the debate between Luther and Erasmus, the latter defending free will and the former denying it.
In light of the Wars of Religion that followed upon the Reformation, Luther's solution to the crisis fomented by nominalism fell into disrepute. The subjectivism implicit in sola fide was to be countered by a new science grounded in mathematical objectivity, and the natural world studied by this science would now take precedence over the divine and human realms. With this third branch of special metaphysics finally taking center stage, modernity comes into being. However, its precise shape was still to be determined. Descartes and Hobbes shared the mechanical conception of nature that underlay the new natural science. But, where the dualist Descartes placed God and the soul outside the mechanical order, the materialist Hobbes interpreted God as but one, albeit grand, material substance among others, and regarded human thought as merely motions in the brain. The sequel was a reformulation of the Luther/Erasmus debate over free will. Having taken the soul to be outside the causal order of nature, Descartes, like Erasmus, was able to affirm freedom. However, for Hobbes, there could be no freedom other than the freedom to act as we desire, where the fact that we desire something is itself entirely determined by material forces outside our control.
The scheme of a good society which it projects is therefore in principle likely to be actualized by men's efforts or its actualization depends much less on chance than does the classical "utopia": chance is to be conquered, not by abandoning the passionate concern with the goods of chance and the goods of the body but through giving free reign to it. The good society in the new sense is possible always and everywhere since men of sufficient brain can transform the most corrupt people, the most corrupt matter, into an incorrupt one by the judicious application of the necessary force. Since man is not by nature ordered toward fixed ends, he is as it were infinitely malleable. This view becomes a settled conviction long before philosophers begin to think of "evolution." Since man is not by nature ordered toward goodness, or since men can become good and remain good only through compulsion, civilization or the activity which makes men good is man's revolt against nature; the human in man is implicitly understood to reside in an Archimedean point outside of nature. The "idealistic" philosophy of freedom supplements and ennobles the "materialistic" philosophy which it presupposes in the very act of negating it. The brain which can transform the political matter soon learns to think of the transformation of every matter or of the conquest of nature. The charm of competence bewitches completely first a few great men and then whole nations and indeed as it were the whole human race. Yet before that grand revolt or emancipation can get under way, the hold which the old modes and orders have over the minds of almost all men must be broken. It cannot be broken by frontal assault, for there does not yet exist an army which has sworn to the new modes and orders. Therefore a most subtle rhetoric is still needed for recruiting the highest officers or the general staff of the new army. The new philosophy lives from the outset in the hope which approaches or equals certainty, of future conquest or of conquest of the future — in the anticipation of an epoch in which the truth will reign, if not in the minds of all men, at any rate in the institutions which mold them. Propaganda is to guarantee the coincidence of philosophy and political power. Philosophy is to fulfill the function of both philosophy and religion. The discovery of the Archimedean point outside of everything given, or the discovery of a radical freedom, promises the conquest of everything given and thus destroys the natural basis of the radical distinction between philosophers and non-philosophers.
Rod Dreher (channelling Hans Boersma):
Boersma talks ... about the theological and philosophical basis of the first thousand years of Christianity. He calls it a “Platonic-Christian synthesis” — that is, the belief that all matter, all nature, is metaphysically anchored in God. That is, that everything that exists receives its very existence from God, and subsists mysteriously in God.
This changed radically in the High Middle Ages for a number of reasons Boersma detailed. The most significant of them were the rise of univocity and nominalism. I’m greatly simplifying here, but univocity means that God is not Being itself, but a category of Being. He sits atop the hierarchy of Being, as its supreme entity. This served to crack the metaphysical bond between God and Nature. As Boersma writes, no longer did earthly objects receive their reality from God’s own being. Rather, they possessed their own being. This effectively makes the created order independent of God.
Then came nominalism, which denies that there is an intrinsic essence in anything. Matter has meaning through an act of will. Ockham and the nominalists did not deny God’s existence, but they said that insofar as anything meant anything, it was because God willed it to be so (this, as distinct from the view that it is part of His nature, because he is in some sense united to Nature). Move God out of the picture and then man’s relationship to Nature is one in which we can do anything we want with it, bound by no natural laws. There is no natural teleology.
These and other factors at work in the West laid the groundwork for the ongoing exile of God from, well, life. (Interestingly, Boersma points out that almost all of this took place before the Reformation, though the Reformation, and the Counter Reformation, accelerated the process already underway.) In the Great Tradition, nothing existed on its own; everything was really connected in God and through God. Modernity — starting with the Late Middle Ages — progressively unraveled the “sacramental tapestry.” Boersma says that only a return to the sacramental vision of the Great Tradition can save the church today from dissolution.