Speaking of Alvin Plantinga (below), this is one of the passages from John Calvin where Calvin describes the innate sense of God that all people possess – which Plantinga employs in his Aquinas/Calvin model for warranted Christian belief.

“There is within the human mind, and indeed by natural instinct, an awareness of divinity. This we take to be beyond controversy.  To prevent anyone from taking refuge in the pretense of ignorance, God himself has implanted in all men a certain understanding of his divine majesty. . . . Men of sound judgment will always be sure that a sense of divinity which can never be effaced is engraved upon men’s minds. Indeed, the perversity of the impious, who though they struggle furiously are unable to extricate themselves from the fear of God, is abundant testimony that this conviction, namely, that there is some God, is naturally inborn in all, and is fixed deep within, as it were in the very marrow.”

from John Calvin, Institutes of the Christian Religion (Philadelphia: Westminster Press, 1960), 43, 45-46.