John Calvin Commentary Jeremiah 9:5

"And they will deceive every one his neighbor, and will not speak the truth: they have taught their tongue to speak lies; they weary themselves to commit iniquity." — Jeremiah 9:5 (ASV)

Jeremiah continues with the same subject. He says that fidelity had so vanished among the Jews that everyone sought to deceive his neighbor. Therefore, it followed that they were without any shame. Some sense of shame at least remains among people when they deal with their own friends; for though they may be entirely given to gain and to indulge in falsehoods, yet when they conduct business with friends, they retain some regard for equity, and shame restrains their wickedness. But when no distinction is made between friends and strangers, it follows that their character has become entirely brutal. This is what the Prophet meant.

And he adds that they spoke not the truth. He now says that they were liars, not just in this or that particular business, but that they were perfidious and deceitful in everything. This statement, then, is not to be limited to some specific acts of fraud; rather, it is as if he had said that they did not know what truth was, or what it was to act in good faith and to speak honestly to their neighbors, for they were entirely imbued with deceit, and no truth could come from their mouths.

And for the same purpose, he says that they had taught their tongues to speak falsehood. This expression is stronger, for he means that they were entirely devoted to deceit, as through long practice they had trained their tongues for this task. The tongue ought to be the representative of the mind, according to the old saying. For why was the tongue created, if not so that people might communicate with one another? For thoughts are hidden, and they emerge when we speak with each other. But the Prophet says that the order of nature was inverted by them, for they had taught their tongues to lie. We also learn from this that they had no fidelity whatsoever, for their very tongues had been trained to deceive. Just as when anyone has learned anything by practice, he does it readily, so when tongues are formed by continual practice and inured to lying, they can do nothing else.

He says at last that they wearied themselves with evil deeds. This is indeed hyperbolic language, yet the Prophet very aptly portrays the deplorable state of the people—that they practiced evil even to the point of exhaustion. Just as when anyone is seized by some foolish lust, he spares no effort and does himself much harm, but does not feel his exhaustion as long as he is engaged, for his ardor deranges him; so he says now that they were exhausted in doing evil. When a hunter pursues game, he endures much more labor than any common worker or farmer. We see that even kings and courtiers, while hunting, are so blinded that they see no danger nor feel any exhaustion. So we find that those devoted to pleasure, when lust draws them here and there, feel no concern for the greatest exhaustion. In this sense, then, the Prophet says that they were exhausted in doing evil, as if he had said that they were so devoted to wickedness that the pleasure of doing evil entirely blinded them and drove them mad.

We now perceive the Prophet’s meaning: He confirms, as I have said, what he had stated before. He had threatened the people with utter ruin; they were complacent and heedless, and despised all his denunciations. He now shows, from God’s nature and office, that ruin was near them, though they did not fear it and thought themselves perfectly safe. But if God is the judge of the world, as will be proven later, how is it possible for him to connive perpetually at such great wickedness? And to show this he also adds—