As to reprobation, I know that many greatly dislike this doctrine—that some are rejected, and that yet no cause can be found in themselves why they thus remain disapproved by God. But there is here need of docility and of a meek spirit, to which Paul also exhorts us, when he says, “O man, who art thou who answerest against God?” (Rom. ix. 20.) For were it lawful to investigate the cause, surely Paul, who had been taken up to the third heaven, might have showed us the way; but he is here silent and drives us away from the indulgence of a bold and an over curious spirit. Since the Holy Spirit by the mouth of Paul restrains the presumption of men, that they may not dare to go beyond this step—that God hardens whom he wills and rejects whom he wills, why do men leap beyond this, except they willfully seek to carry on war with God? and yet they pretend modesty, and under this pretext they seek to bury the doctrine of election; we ought, they say, to speak soberly of mysteries. This last sentence I allow fully; but what is our sobriety but our docility? that is, when we embrace what God declares in his word, and never allow ourselves to investigate more than what he teaches us. But they would extinguish God’s word; nay, they dare openly to pronounce blasphemies against God, and to find fault with the Spirit, who has spoken by the prophets and the apostles.
We indeed see that there are many devils who preach modesty, when their object is to suppress the light and this chief doctrine, the main basis of our salvation; and they exhort wicked edicts from the ignorant and the slumbering, as though it were in the power of men, by babbling about things unknown, and by barbarously mixing all things together, to thrust God as it were from his celestial throne. This is horribly monstrous, and ought to be detested by all; for it would be better that all the empires of the world should be swallowed up in the lowest depths, than that mortal creatures should raise themselves up as it were into heaven, and attempt to penetrate into the secret things of God. But, however, when the whole world either assail this doctrine by barking, or seek to subvert it by threats and terror, or when all in various ways manifest their rage, and when they roll thunders who seem to themselves to be very powerful, it behoves us to hold fast this doctrine, that God alone is the author of our salvation, because he has been pleased freely to elect us, and also that he possesses power over all the human race, so that some, according to his will, are elected and some are rejected, and that he ever acts justly, and holds secret the cause both of election and of reprobation. But it is no wonder that we are so blind for we are stupid by nature, nay, blind altogether; and were we angels, it would be still our duty reverently to regard the manifold wisdom of God, which no human minds, no, not even angelic minds, can fully comprehend.
John Calvin, Commentary on Malachi 1:2-6
(From: The Twelve Minor Prophets, V. 481-482)