More Contrasts between Calvin and Aquinas!
Second, Calvin emphasizes explicitly and repeatedly the effect of the fall on man’s knowledge of God. Though men have a naturally implanted knowledge of God given to them by and in creation, this knowledge never develops into a “true” knowledge in the sense of a practical and religious principle which leads them to worship God aright. Let me put that in my own words, but they are words which, I think, rightly embody Calvin’s view. He believes that men have a natural revelation of God, but that this natural revelation never results in a natural theology which can guide them appropriately in worship or in life in general. This emphasis is practically absent in Thomas. Listen to Calvin:
It must also be remarked, that, though they strive against their own natural understanding, and desire not only to banish him thence, but even to annihilate him in heaven, their insensibility can never prevail so as to prevent God from sometimes recalling them to his tribunal. But as no dread restrains them from violent opposition to the divine will, it is evident, as long as they are carried away with such a blind impetuosity, that they are governed by a brutish forgetfulness of God. 
At length they involve themselves in such a vast accumulation of errors, that those sparks which enable them to discover the glory of God are smothered, and at last extinguished by the criminal darkness of iniquity. That seed, which it is impossible to eradicate, a sense of the existence of a Deity, yet remains; but so corrupted as to produce only the worst of fruits. Yet this is a further proof of what I now contend for, that the idea of God is naturally engraved on the hearts of men, since necessity extorts a confession of it, even from reprobates themselves. In a moment of tranquility they facetiously mock the Divine Being, and with loquacious impertinence in many derogate from his power. But if any despair oppress them, it stimulates them to seek him, and dictates concise prayers, which prove that they are not altogether ignorant of God, but that what ought to have appeared before had been suppressed by obstinacy. 
Third, this very different assessment of the effect of the fall on man’s knowledge of God comes to concrete expression in the very different use which Thomas and Calvin make of a classic passage on the subject. I have in mind, of course, Psalm 53:1 which reads in part: “The fool has said in his heart, “There is no God,” They are corrupt, and have committed abominable injustice; There is no one who does good.” Both Thomas and Calvin cite this text, but how different is the use they make of it!
Thomas sees it as proof that the existence of God is not self-evident. He takes at face value the fool’s assertion that there is no God. Aquinas says: “On the contrary, no one can mentally admit the opposite of what is self-evident; as the Philosopher … states concerning the first principles of demonstration. But the opposite of the proposition “God is” can be mentally admitted: The fool hath said in his heart, There is no God (Ps. Lii. 1). Therefore that God exists is not self-evident.” 
Calvin, on the other hand, takes it as evidence of the deep depravity of the fool. The fool denies a knowledge of God that is ineradicably implanted in him. Here is Calvin’s comment in the Institutes on Psalm 53:1 with some context:
While experience testifies that the seeds of religion are sown by God in every heart, we scarcely find one man in a hundred who cherishes what he has received, and not one in whom they grow to maturity, much less bear fruit in due season. Some perhaps grow vain in their own superstitions, while others revolt from God with intentional wickedness; but all degenerate from the true knowledge of him. The fact is, that no genuine piety remains in the world. But, in saying that some fall into superstition through error, I would not insinuate that their ignorance excuses them from guilt; because their blindness is always connected with pride, vanity, and contumacy. 
David’s assertion, that “the fool hath said in his heart, There is no God,” is primarily, as we shall soon see in another place, to be restricted to those who extinguish the light of nature and willfully stupefy themselves. 
 John Calvin, Institutes of the Christian Religion (Book 1, Chapter 4, Section 2)
 Institutes of the Christian Religion (Book 1, Chapter 4, Section 4)
 Thomas Aquinas, Summa Theologica (Volume 1, Question 2, Article 1)
 Institutes of the Christian Religion (Book 1, Chapter 4, Section 1)
 Institutes of the Christian Religion (Book 1, Chapter 4, Section 2)