Chapter III of Book I of Calvin's Institutes: "The Knowledge of God Has Been Naturally Implanted in the Minds of Men."
Calvin's point in this short chapter is that humans are naturally religious. He says that a certain type of divine knowledge has been "inscribed" or "implanted" in our hearts, so much so that no matter how primitive a people group you could locate, they would have some knowledge of the divine in their hearts. Calvin says that even man's constant idolatry is proof of this--why else would haughty man be so eager to continuously set up something higher than himself to worship?
Calvin acknowledges that religion has from time to time been imposed upon people to gain an advantage over them, but says that this would never have been successful were it not for the natural tendency and innate need to worship. So strong is this need for worship, so real the knowledge of a transcendent God, that even those who ardently deny God's existence express great fear and dread of suffering his wrath.
Calvin finishes by saying that this innate knowledge of the divine and the need to worship, implanted in us, is what sets us above the beasts.
I'm not sure what to make of this chapter of The Institutes. As was mentioned with the last chapter, we need to be sure to read this one in the context of what is coming after, specifically as Calvin moves from describing man in his primitive (pre-fall) state and into describing man's relationship to God now, after sin and chaos have entered the scene. With that said, Calvin isn't merely trying to describe man in his purity here, as evidenced by his references to the pagans who have knowledge of God as part of their nature. As it relates to this discussion, I can't help but wonder whether or not it is proper for us to describe man's lack and corruption as an innate "knowledge of God." That is, I'm not sure that the answer is implied in the questions man asks about the world, life, and existence. It seems that Calvin assumes, however, that this is the case.
I also think it is questionable to refer to man's religious nature as evidence that all people have innate knowledge of God. Do we see someone worshiping an idol and claim that this person has knowledge of God? Is it right to call this idol "God," if we mean to refer to the one true God revealed in Jesus Christ?
Of course, there is a way to save Calvin from this condemnation. We can understand him as a Christian theologian with a theological starting point, explaining man's religiosity and idolatry in light of the revelation of God and man effected in Jesus Christ. If this is the case, although Calvin appears to be starting from the bottom up and moving from man to God in this chapter, it would probably be better to see him as assuming the biblical witness and explaining the phenomena of man's existence with a theological or Christological starting point. From what we know of Calvin, I'm quite certain at this point that this is how we should interpret him.