Surely, the first foundation of righteousness is the worship of God. When this is overthrown, all the remaining parts of righteousness, like the pieces of a shattered and fallen building, are mangled and scattered. What kind of righteousness will you call it not to harass men with theft and plundering if, through impious sacrilege you, at the same time, deprive God’s majesty of its glory? Or that you do not defile your body with fornication if, with your blasphemies, you profane God’s most holy name? Or that you do not slay a man if you strive to kill and to quench the remembrance of God? It is vain to cry up righteousness without religion. This is as unreasonable as to display a mutilated, decapitated body as something beautiful. Not only is religion the chief part but the very soul, whereby the whole breathes and thrives. And, apart from the fear of God, men do not preserve equity and love among themselves.
Therefore, we call the worship of God the beginning and foundation of righteousness. When it is removed, whatever equity, continence, or temperance men practice among themselves is, in God’s sight, empty and worthless. We call it source and spirit because, from it, men learn to live with one another in moderation and without doing injury if they honor God as judge of right and wrong. Accordingly, in the First Table [of the Ten Commandments], God instructs us in piety and the proper duties of religion by which we are to worship His majesty. The Second Table prescribes how, in accordance with the fear of His name, we ought to conduct ourselves in human society. In this way, our Lord, as the Evangelists relate, summarizes the whole law under two heads: that “you shall love the Lord your God with all your heart and with all your soul and with all your strength and with all your mind, and your neighbor as yourself” [Luke 10.27; cf. Matthew 22.37, 39]. You see that, of the two parts in which the law consists, one he directs to God. The other he applies to men. – John Calvin (1509-1564), from Institutes of the Christian Religion, 2.8.11.