As Calvin begins, he gives an important caveat - the knowledge of God he's talking about he limits in this way:
Here I do not yet touch upon the sort of knowledge with which men, in themselves lost and accursed, apprehend God the Redeemer in Christ the Mediator; but I speak only of the primal and simple knowledge to which the very order of nature would have led us if Adam had remained upright. In this ruin of mankind no one now experiences God either as Father or as Author of salvation, or favorable in any way, until Christ the Mediator comes forward to reconcile him to us. (p. 40, Institutes of the Christian Religion)This first book involves God as Creator - not as Redeemer, which he'll take up in book 2 (or 2-4, really).
He next discusses the connection of knowledge of God with that trust and reverence that characterizes piety. True knowledge of God, Calvin writes,
serve first to teach us fear and reverence; secondly, with it as our guide and teacher, we should learn to seek every good from him, and, having received it, to credit it to his account. For how can the thought of God penetrate your mind without your realizing immediately that, since you are his handiwork, you have been made over and bound to his command by right of creation, that you owe your life to him?-that whatever you undertake, whatever you do, ought to be ascribed to him? If this be so, it now assuredly follows that your life is wickedly corrupt unless it be disposed to his service, seeing that his will ought for us to be the law by which we live. Again, you cannot behold him clearly unless you acknowledge him to be the fountainhead and source of every good. From this too would arise the desire to cleave to him and trust in him, but for the fact that man's depravity seduces his mind from rightly seeking him. (p. 42, Institutes of the Christian Religion)Calvin is very clear here and elsewhere to note that the Fall of Adam wrecked our nature in such a way that seeking God in Spirit and Truth is impossible. Knowledge in a true sense accompanies love and reverence for God - and ultimately that, as Calvin writes, is ours only if we are in Christ, and our hearts of stone replaced by hearts of flesh. With love and reverence for God comes the willingness to submit fully to God's own revelation of Himself as defining who God is. I suspect Calvin's day wasn't so different than ours - that is, many people said, if not in so many words, "my God isn't like that" when faced with a difficult doctrine concerning God and His works (e.g. election, the doctrine of Hell, God's ordaining evil acts of men, etc). But if we are truly reverent - truly trusting in Him for all things, then will we construct a god of our own liking? Or, would we submit to His Word and what He says about Himself in it?
A pious mind, Calvin writes, seeks to know God and His will only as He has revealed Himself - for to construct false notions of God is an act of distrust - an act of irreverence. Finally, to add a comment concerning a definition of piety that is contained in a footnote, and not the text of the 1559 Institutes - Calvin in 1937 wrote:
The gist of true piety does not consist in a fear which would gladly flee the judgment of God, but ... rather in a pure and true zeal which loves God altogether as Father, and reveres him truly as lord, embraces his justice and dreads to offend him more than to die. (p. 40, footnote 1, Institutes of the Christian Religion)May this definition of piety characterize us -