And they have built the high places of Tophet, which is in the Valley of the Son of Hinnom, to burn their sons and their daughters in the fire, which I did not command, nor did it come into My heart. (Jeremiah 7:31)
We hence perceive that there is no end of sinning, when men give themselves up to their own inventions; for God surrenders those to Satan, that they may be led by the spirit of giddiness and of madness and of stupidity. Let us therefore learn ever to regard what God approves: and let this be the very beginning of our inquiry, whenever we undertake anything, whether God commands it; and this course ought especially to be observed with regard to his worship; for, as it has been already stated, religion is especially founded on faith, and faith is based on the word of God: and hence it is here added —
Which I commanded them not, and which never came to my mind This reason ought to be carefully noticed, for God here cuts off from men every occasion for making evasions, since he condemns by this one phrase, “I have not commanded them,” whatever the Jews devised. There is then no other argument needed to condemn superstitions, than that they are not commanded by God: for when men allow themselves to worship God according to their own fancies, and attend not to his commands, they pervert true religion.
And if this principle was adopted by the Papists, all those fictitious modes of worship, in which they absurdly exercise themselves, would fall to the ground. It is indeed a horrible thing for the Papists to seek to discharge their duties towards God by performing their own superstitions. There is an immense number of them, as it is well known, and as it manifestly appears. Were they to admit this principle, that we cannot rightly worship God except by obeying his word, they would be delivered from their deep abyss of error. The Prophet’s words then are very important, when he says, that God had commanded no such thing, and that it never came to his mind; as though he had said, that men assume too much wisdom, when they devise what he never required, nay, what he never knew.
John Calvin, Commentaries on the book of the prophet Jeremiah and the Lamentations, trans. and ed. John Owen (Geneva, 1589) in Calvin’s commentaries (22 vols, Grand Rapids, 1993), ix, 413-14.