John Calvin Commentary Jeremiah 7:8

"Behold, ye trust in lying words, that cannot profit." — Jeremiah 7:8 (ASV)

He again teaches what we observed yesterday — that the glorying of the Jews was foolish, while they boasted of the Temple and of their sacrifices to God. He calls their boastings the words of falsehood, as we have explained, because they completely turned what God had instituted to a contrary purpose.

It was His will that sacrifices should be offered to Him in the Temple — for what purpose? To preserve unity of faith among the whole people. And sacrifices, what was their design? To show the people that they deserved eternal death, and also that they were to flee to God for mercy, there being no other expiation but the blood of Christ.

But there was no repentance; they were not sorry for their sins. Indeed, as we will shortly see, they took liberty to indulge more in them because of their ceremonies, which, however, ought to have been the means of leading them to repentance. They were then the words of falsehood when they separated the signs from their purposes.

The reality and the sign ought indeed to be distinguished from each other, but it is an intolerable divorce when people cling to mere signs and overlook the reality. In the sacrifices, there was the reality I have now mentioned: they were reminded by the spectacle that they were worthy of eternal death; and then, they were to exercise repentance and thus flee to God’s mercy. Since Christ was not taken into account, and there was no care for repentance, no sorrow for sins, no fear of God, and no humility, it was an impious separation of what ought to have been united.

So now we see more clearly why the Prophet designates as words of falsehood that false glorying in which hypocrites indulge, in opposition to God, when they would have Him satisfied with mere ceremonies. Hence he adds that they were words that could not profit, as though he had said, "As you seek to trifle with God, so He will also frustrate your design."

It is indeed certain that they dealt dishonestly with God when they attempted to satisfy His judgment by frigid ceremonies. He therefore shows that a reward was prepared for them, for they would eventually find that no fruit would come from their false dealings.