Update: Per Andrew’s comment, I amended the below to include the footnote and clarify the editors’ position.
For John Calvin, the knowledge of God is necessarily tied to the experience of piety, by which Calvin means “that reverence joined with love of God which the knowledge of his benefits induces.”
The relationship, however, between our knowledge of God and our piety is less clear than it initially seems. In the most readable translation of Calvin’s Institutes, Ford Lewis Battles and John T. McNeill insert as a heading to the first paragraph of Book I, Chapter 2, “Piety is requisite for the knowledge of God.” They are so intent, in fact, on this point that they reinforce the exact same point in a footnote: “It is a favorite emphasis in Calvin that pietas, piety, in which reverence and love fo God are joined, is prerequisite to any true knowledge of God.”
The only problem with this, however, is that Calvin nowhere suggests that piety is a prerequisite to the knowledge of God. While Calvin is careful to point out that our mind cannot apprehend God without honoring him, he does not suggest that honor must precede apprehension. While piety is necessarily tied to our knowledge of God, it is the fruit of our knowledge of Him, not the precursor to it.
The point is crucial: the notion that piety is a precursor to our knowledge of God commits Calvin to something like “prevenient grace.” Calvin is careful to point out later on in the text that true piety does not exist on the earth. If piety was a pre-requisite to the knowledge of God, then there would have to be a regenerative action by God in humans prior to his self-revelation to us.
I suggest that McNeill and Battle’s emphasis on piety as a prerequiste is mistaken, then.