From Calvin’s commentary on 1 Cor 2:14-16:
14. But the animal man. By the animal man he does not mean (as is commonly thought) the man that is given up to gross lusts, or, as they say, to his own sensuality, but any man that is endowed with nothing more than the faculties of nature. This appears from the corresponding term, for he draws a comparison between the animal man and the spiritual As the latter denotes the man whose understanding is regulated by the illumination of the Spirit of God, there can be no doubt that the former denotes the man that is left in a purely natural condition, as they speak. For the soul belongs to nature, but the Spirit is of supernatural communication.
He returns to what he had previously touched upon, for his object is to remove a stumblingblock which might stand in the way of the weak — that there were so many that despised the gospel. He shows that we ought to make no account of a contempt of such a nature as proceeds from ignorance, and that it ought, consequently, to be no hindrance in the way of our going forward in the race of faith, unless perhaps we choose to shut our eyes upon the brightness of the sun, because it is not seen by the blind. It would, however, argue great ingratitude in any individual, when God bestows upon him a special favor, to reject it, on the ground of its not being common to all, whereas, on the contrary, its very rareness ought to enhance its value.
For they are foolishness to him, neither can he know them. “The doctrine of the gospel,” says he, “is insipid in the view of all that are wise merely in the view of man. But whence comes this? It is from their own blindness. In what respect, then, does this detract from the majesty of the gospel?” In short, while ignorant persons depreciate the gospel, because they measure its value by the estimation in which it is held by men, Paul derives an argument from this for extolling more highly its dignity. For he teaches that the reason why it is contemned is that it is unknown, and that the reason why it is unknown is that it is too profound and sublime to be apprehended by the understanding of man. What a superior wisdom this is, which so far transcends all human understanding, that man cannot have so much as a taste of it! While, however, Paul here tacitly imputes it to the pride of the flesh, that mankind dare to condemn as foolish what they do not comprehend, he at the same time shows how great is the weakness or rather bluntness of the human understanding, when he declares it to be incapable of spiritual apprehension. For he teaches, that it is not owing simply to the obstinacy of the human will, but to the impotency, also, of the understanding, that man does not attain to the things of the Spirit. Had he said that men are not willing to be wise, that indeed would have been true, but he states farther that they are not able. Hence we infer, that faith is not in one’s own power, but is divinely conferred.
Because they are spiritually discerned That is, the Spirit of God, from whom the doctrine of the gospel comes, is its only true interpreter, to open it up to us. Hence in judging of it, men’s minds must of necessity be in blindness until they are enlightened by the Spirit of God. Hence infer, that all mankind are by nature destitute of the Spirit of God: otherwise the argument would be inconclusive. It is from the Spirit of God, it is true, that we have that feeble spark of reason which we all enjoy; but at present we are speaking of that special discovery of heavenly wisdom which God vouchsafes to his sons alone. Hence the more insufferable the ignorance of those who imagine that the gospel is offered to mankind in common in such a way that all indiscriminately are free to embrace salvation by faith.
Calvin, John. Calvin’s Complete Bible Commentaries (With Active Table of Contents in Biblical Order) (Kindle Locations 446320-446324). . Kindle Edition.