According to John Calvin, the knowledge of God "is that by which we not only conceive that there is a God but also grasp what befits us and is proper to his glory, in fine, what is to our advantage to know of Him."
Calvin's definition is masterful. Allow me to tease out two sides to it:
The knowledge of God is that by which we grasp "what befits us." Calvin is perfectly clear that there are limits on our pursuits of knowledge. Speculation, wherein we reach too highly, leads to idolatry, for we seek to know that which is no longer fitting for us to know. For Calvin, the knowledge of God carries within it limitations. We do not know God as he is in himself, but only as he manifests Himself.
The knowledge of God is that by which we grasp "what is proper to his glory, in fine, what is to our advantage to know of Him." Here we see the second aspect to the knowledge of God. For humans, to know God is to know that He is good. Calvin writes in the next paragraph, "It will not suffice simply to hold that there is One whom all ought to honor and adore, unless we are also persuaded that he is the fountain of every good, and that we must seek nothing elsewhere than in Him."
Calvin does not reach the knowledge of God as summum bonum--the medieval characterization of God as "supreme good"--through a methodological abstraction. I am tempted to say that Calvin is frontloading his theology here; he is building in a doctrine of God that necessarily has methodological implications.
Regardless, it is clear that Calvin thinks that the God who we know is the God who is for us. It is tempting to mimic Barth here: the God we know is the God for us. He is a God whose being is good. But the God we know is the God for us. Not only is he good--he is good in ways that that specifically benefit us, and if we do not see him as such, we do not see him at all.
Matthew Lee Anderson is the Founder and Lead Writer of Mere Orthodoxy. He is the author of Earthen Vessels: Why Our Bodies Matter to our Faith and The End of Our Exploring: A Book about Questioning and the Confidence of Faith. Follow him on Twitter or on Facebook.