...they ignored the careful methodological distinctions Thomas [Aquinas] made between what could be known about God by reason as opposed to what faith alone could know; and this overreaching led to a peculiar form of modern gnosticism, as Mortimer Adler noticed so acutely in his Aquinas Lecture at Marquette University in 1938, called St. Thomas and the Gentiles:
"Modern gnosticism results from the efforts of thinkers to answer purely theological questions by merely natural means. The theodicy of Spinoza, the knowledge of the Absolute in Hegel, the discussion of the order of the universe in time and space by Whitehead, are examples of philosophy exceeding its domain. Though lacking faith, these philosophers do not seem able to regain the position of natural reason in Greek antiquity. Christianity has somehow been too much for them. When we learn that Hegel’s formative influences were theology and the classics, we can see the root of all his confusions. In a paradoxical sense, then, all modern philosophers are Christian, even when they are skeptical, as Hume, or agnostic, as Kant. Christianity has made problems for them which they cannot solve without faith, but which they will not refrain from discussing in rational terms."
Marquette University Press keeps the entire St. Thomas Aquinas Lecture Series in print. Dr. Adler's was the second. The fourteenth is St. Thomas and the World State by Robert M. Hutchins (1949).