John Calvin Commentary Isaiah 48:1

"Hear ye this, O house of Jacob, who are called by the name of Israel, and are come forth out of the waters of Judah; who swear by the name of Jehovah, and make mention of the God of Israel, but not in truth, nor in righteousness" — Isaiah 48:1 (ASV)

Hear this, O house of Jacob. He now directs his discourse to the Jews, whom he also primarily had in mind throughout the preceding chapter. For he was not sent to the Babylonians; rather, he addresses them in such a way that he wished the Jews, to whom he had been especially appointed, would hear him.

Accordingly, he foretold the destruction of the Babylonians so that the Jews might calmly wait for deliverance, not be terrified by the greatness and power of their enemies, and, relying on these promises, stand unmoved against all temptations. But because the Jews were obstinate and did not believe those promises, and because Isaiah foresaw how great their hard-heartedness and obstinacy would be during their captivity, he reproves them with greater severity.

Ezekiel shows still more clearly how inveterate their unbelief was when they murmured against God, cast away all confidence, and cared no more about the promises of God than about empty fables. It was not without reason, therefore, that Isaiah made use of such vehement language, in order to show that they offered the highest insult to God by refusing to rely on his grace.

Who are called by the name of Israel. He addresses “Israel,” but an Israel that was actually spurious and at that time had nothing more than the name. For he does not use this honorable name to mention them respectfully, but rather to put their false boasting to shame, because they had no right to glory in this empty title, from the truth of which they were widely estranged. Why did God honor Jacob with this name, if not because he proved himself to be courageous and invincible in adversity? This appeared from that wrestling in which he contended with God; for when the Lord tries by various afflictions, he enters, as it were, into debate with us (Genesis 32:25). How, then, did this name apply to his posterity, if they were cast down and threw away all hope in adversity?

Who have come out from the waters of Judah. He next reproaches them for being descended from the holy fathers, and yet being utterly unlike them. By “the waters of Judah,” he metaphorically means the source and fountain from which the Jews proceeded; for I do not approve of the childish attempt of the Jewish writers to explain the metaphor, which is borrowed in a highly natural manner from waters that flow from a distant place.

Who swear by the name of Jehovah. Having censured them for being the degenerate and wicked children of holy fathers, he adds that they falsely pretend to the worship of God and to a semblance of piety from which they are widely distant. Now, as “swearing” is a kind of worship of God, he here puts one department for the whole class, by a figure of speech in which a part is taken for the whole.

Just as idolaters offer an insult to God when they swear by their idols, in the same way sincere worshippers of God render honor to God by using his name in oaths; for they acknowledge that they have one God, in whose name they glory. But here he attacks hypocrites who, with open mouth, loudly boasted of the name of God and frequently mentioned his name, yet in their hearts were greatly opposed to him.

For this reason, he says, not in truth nor in righteousness. In this phrase, he employs the word “righteousness” to denote integrity and sincerity of heart, without which nothing can be acceptable to God. Or rather, “righteousness” and “truth” are synonymous terms, as if he had said that it was mere pretense and hypocrisy to profess that they were the people of the true God, because their treachery openly proclaimed their falsehood.