John Calvin Commentary Isaiah 42:8

"I am Jehovah, that is my name; and my glory will I not give to another, neither my praise unto graven images." — Isaiah 42:8 (ASV)

I am Jehovah. From this, understand the nature and extent of the disease of unbelief, since the Lord can hardly find words adequate to express its cure. By nature, we are prone to distrust and do not believe God when He speaks, until He entirely subdues our stubbornness. Besides, we continually fall back into the same fault through our fickleness, unless He employs many bridles to restrain us. Again, therefore, He returns to that confirmation we discussed previously, so that His promises may remain unshaken.

This is my name. הוא (hu) is sometimes taken for a substantive, so as to be a proper name of God; but I explain it in a more simple manner, “It is my name,” that is, “Jehovah is my own name, and cannot lawfully be given to any other.” In a word, by this expression He seals all that was said about the office of Christ, and adds, as it were, a seal to the promise: “He who declares these things testifies that He alone is God, and that this name dwells in Him alone.”

And I will not give my glory to another; that is, “I will not permit my glory to be diminished, which it would be if I were found to be false or fickle in my promises.” He therefore declares that He will abide by His promises, because He wishes to vindicate His glory and preserve it intact, so that it may not be diminished in any respect.

This is a remarkable passage, by which we are taught that the glory of God is chiefly visible in His fulfillment of what He has promised. And thus we obtain a special confirmation of our faith: that the Lord never deceives, never swerves from His promises, and nothing can hinder what He has once determined. But since Satan, by amazing schemes, endeavors to obscure this glory of God and to give it to men and to false gods, He therefore testifies that He will not permit Himself to be regarded as fickle or deceitful in His promises.

Nor my praise to graven images. A contrast is drawn between the only God and idols with reference to time; for, had God not been the Redeemer of His people, unbelievers would have boasted as if true religion had been false and useless. God therefore declares that He will not permit wicked men to triumph by oppressing the Church; and, beyond all doubt, God has until now spared us, and still deals so gently with us, so that He may not expose His Gospel to the blasphemous reproaches of the Papists. We ought to draw from this a universal doctrine, namely, that the Lord wishes that His glory may remain unimpaired; for He defends and maintains it everywhere with the utmost zeal, in order to show that He is exceedingly jealous of it (Exodus 20:5), and does not permit the smallest part of it to be given to another.