John Calvin Commentary John 12:38

"that the word of Isaiah the prophet might be fulfilled, which he spake, Lord, who hath believed our report? And to whom hath the arm of the Lord been revealed?" — John 12:38 (ASV)

That the saying of Isaiah the prophet might be fulfilled. John does not mean that the prediction imposed a necessity on the Jews, for Isaiah (Isaiah 53:1; Romans 10:16) uttered nothing but what the Lord revealed to him from the secret treasures of his purpose. Indeed, it must have happened, even if the prophet had not spoken of it. However, since people would not have known what would take place if God had not testified through the prophet, the Evangelist places before our eyes in the prediction, as in a mirror, what would otherwise have appeared to people obscure and almost incredible.

Lord, who hath believed? This sentence contains two clauses. In the former, Isaiah, having begun to speak of Christ and foreseeing that all that he proclaims concerning Christ, and all that will afterwards be made known by the Apostles, will be generally rejected by the Jews, exclaims, as if in astonishment at something strange and monstrous, Lord, who shall believe our report, or, our speech?

To whom hath the arm of the Lord been revealed? In this second clause, he assigns the reason why they are few; and that reason is that people do not attain it by their own strength, and God does not illuminate all without distinction, but bestows the grace of his Holy Spirit on very few.

And if among the Jews the obstinate unbelief of many ought not to have been an obstacle to believers, though they were few in number, the same argument ought to persuade us today not to be ashamed of the Gospel, though it has few disciples.

But we ought first to observe the reason that is added: what makes people believers is not their own sagacity, but the revelation of God.

The word arm, it is well known, denotes power. The prophet declares that the arm of God, which is contained in the doctrine of the Gospel, lies hidden until it is revealed, and at the same time testifies that all are not indiscriminately partakers of this revelation.

Hence it follows that many are left in their blindness, destitute of inward light, because hearing they do not hear (Matthew 13:13).