John Calvin Commentary Hebrews 12:26

"whose voice then shook the earth: but now he hath promised, saying, Yet once more will I make to tremble not the earth only, but also the heaven." — Hebrews 12:26 (ASV)

Whose voice then shook the earth, etc. Though God shook the earth when he published his Law, yet he shows that he now speaks more gloriously, for he shakes both earth and heaven. He quotes on this subject the testimony of the Prophet Haggai, though he does not give the words literally. But as the Prophet foretells a future shaking of the earth and the heaven, the Apostle borrows the idea to teach us that the voice of the Gospel not only thunders through the earth but also penetrates above the heavens.

But that the Prophet speaks of Christ’s kingdom is beyond any dispute, for it immediately follows in the same passage: I will shake all nations; and come shall the desire of all nations, and I will fill this house with glory. However, it is certain that neither have all nations been gathered into one body, except under the banner of Christ, nor has there been any desire in which we ought to acquiesce, except in Christ alone, nor was the temple of Solomon exceeded in glory until the magnificence of Christ became known throughout the whole world.

The Prophet, then, undoubtedly refers to the time of Christ. But if at the commencement of Christ’s kingdom, not only were the lower parts of the world shaken, but his power also reached the heaven, the Apostle justly concludes that the doctrine of the Gospel is more sublime than that of the Law, and ought to be more distinctly heard by all creatures.