John Calvin Commentary Isaiah 66:15

"For, behold, Jehovah will come with fire, and his chariots shall be like the whirlwind; to render his anger with fierceness, and his rebuke with flames of fire." — Isaiah 66:15 (ASV)

For, behold, Jehovah will come in fire. The object of this (ὑποτύπωσις) lively description is that believers, when they see worthless men laughing at their distresses and growing more and more insolent, may not on that account turn aside from the right path or lose courage. For He intended not only to strike wicked men, who are moved by no threats and scorn all instruction, but also to comfort good people, so that they may feel that they are happy because they are under God’s protection, and may not align themselves with the wicked on account of the prosperity of all their undertakings.

Their advantage is, therefore, what He chiefly has in view, so that they may be satisfied with God’s protection and grace. But it may be doubted whether or not He includes the Last Judgment, along with the temporal punishments with which He now begins to chastise the wicked. For my own part, I have no doubt that He intends to include that judgment also, along with those which were only the forerunners of eternal destruction.

Will come. This began to be accomplished when, by carrying the people away to Babylon, God took vengeance on domestic foes. Next, when the time of the deliverance was accomplished, He attacked the wicked Gentiles more severely with an armed force and did not cease to give other and various proofs of His approach, by which He showed Himself to be present with the elect people, and came in fire to judge their enemies.

Lastly, we know that He will come in fire at the Last Day to take vengeance on all the wicked. But this passage ought not to be limited solely to the Last Judgment, for it also encompasses all the other events. Yet these threats, as we shall see shortly, are especially directed by the Prophet against hypocritical Jews.

These metaphorical expressions are very customary in Scripture, for we could not comprehend this dreadful judgment of God in any other way than by the Prophets using metaphors drawn from known and familiar objects. (See 2 Thessalonians 1:8; 2 Peter 3:7.)

By means of them, the prophets endeavor to make a deep impression on our senses so that, struck with the true fear of God, we may not envy the wicked, for whom such dreadful vengeance is prepared.

Hence we see how trivial and useless are the speculations of the Sophists, who dispute about the refined nature and qualities of that fire. For the purpose of Scripture is to show us, using figures of speech, the dreadful judgment of God, which otherwise we could not imagine or understand. This is still more evident from the word “sword,” in the following verse; for it conveys the same meaning.