John Calvin Commentary Isaiah 40:18

"To whom then will ye liken God? or what likeness will ye compare unto him?" — Isaiah 40:18 (ASV)

To whom then have you likened God? The Jews were in great danger from another temptation, for there was reason to believe that the Assyrians and Babylonians would not have obtained so many victories without the assistance of their gods. From this, the Jews might naturally conclude, “Of what use is it to us to have a unique way of worshipping God that differs from other nations? For our enemies fight under the favor and protection of heaven, while we are not helped by any assistance from the God whom we worship.”

There can also be no doubt that the captives were taunted by unbelievers, as is evident from other passages (Psalms 137:3; Lamentations 2:15). So that true religion might not be ruined among the Jews on account of the calamity they had suffered, God rises up and proclaims that a grievous injury is done to Him if believers, discouraged by adversity, turn aside to the idols and superstitions of the Gentiles. Thus He confirms them in the faith of the promises, so that they may not sink under the weight of the punishments they endure.

The Prophet, as we previously suggested, does not address merely the men of his own age but also posterity. This posterity would face an even more severe contest with the mockeries of the nations whose captives they were, and also with bad examples and customs. For when, as a consequence of being mingled with heathen nations, they daily witnessed many corruptions of piety, it was more difficult for them to persevere steadfastly.

So that they might not entertain the foolish notion that high prosperity accompanied the worshippers of false gods, the Prophet confronts this error. He reminds them that God, whom they and their fathers worshipped, should not be compared with the gods of the Gentiles. For these idols were made by men and were composed of gold or silver, wood or stone; but God created all things. Therefore, the highest injury is done to God, not only by comparing His majesty with things of no value, but even by not placing Him far above all the angels and everything that is considered divine.

When Paul uses this passage (Acts 17:29) as a proof against idolaters, or at least quotes the Prophet's words, he does not distort them from their true meaning. Indeed, he infers from them that to make any image of God is exceedingly wicked. Meanwhile, the Prophet, while guarding the Jews against distrust, simultaneously condemns the superstitions of the Gentiles and declares that it is inconsistent with God's nature to be represented by painting or by any kind of likeness. This shows clearly that Paul’s doctrine fully agrees with it. For the Prophet, after having shown that God's power is infinite (since He holds all things in His fist), finally concludes, “To whom then will you liken me? for no image that is formed will have any likeness or resemblance to me.”

Or, what resemblance will you appoint to him? This is a useful doctrine and worthy of observation. For if there were nothing more than this single passage, it would be perfectly sufficient for refuting the inventions by which Papists deceive themselves when they think that they have a right to represent God by outward figures. The Prophet declares that it is impossible to make from dead matter an image that will have any resemblance to the glory of God. He openly rejects idols and does not even speak of their worship, but affirms that to manufacture and set them up before God is wicked and abominable. The Scripture is full of such proofs. Moses warned a people prone to this vice,

“You saw no image or shape in the mountain; you only heard a voice. See then and beware that you are not led astray so as to make for yourself any image.”
(Deuteronomy 4:12, 15).

In order to know God, therefore, we must not make a likeness of Him according to our own fancy; instead, we must turn to the Word, in which His living image is presented to us. Satisfied with that communication, let us not attempt anything else of our own. Other ways and methods, such as idols and images, teach us vanity and falsehood, not truth, as Jeremiah beautifully says, “The wood is the instruction of vanities” (Jeremiah 10:8), and Habakkuk, “His graven image is falsehood” (Habakkuk 2:18).

When the Lord sometimes compares Himself to a lion, a bear, a man, or other objects, this has nothing to do with images, as the Papists imagine. Instead, by those metaphors, God's kindness and mercy, or His wrath and displeasure, and other things of the same nature, are expressed. For God cannot reveal Himself to us in any other way than by a comparison with things that we know. In short, if it were lawful to make or set up an image of God, that would be a point of resemblance to the gods of the Gentiles, and this declaration of the Prophet could not be maintained.