That which is born of the flesh. By reasoning from contraries, he argues that the kingdom of God is shut against us, unless an entrance be opened to us by a new birth, (palingenesia ) For he takes for granted, that we cannot enter into the kingdom of God unless we are spiritual. But we bring nothing from the womb but a carnal nature. Therefore it follows, that we are naturally banished from the kingdom of God, and, having been deprived of the heavenly life, remain under the yoke of death. Besides, when Christ argues here, that men must be born again, because they are only flesh, he undoubtedly comprehends all mankind under the term flesh. By the flesh, therefore, is meant in this place not the body, but the soul also, and consequently every part of it. When the Popish divines restrict the word to that part which they call sensual, they do so in utter ignorance of its meaning; [1] for Christ must in that case have used an inconclusive argument, that we need a second birth, because part of us is corrupt. But if the flesh is contrasted with the Spirit, as a corrupt thing is contrasted with what is uncorrupted, a crooked thing with what is straight, a polluted thing with what is holy, a contaminated thing with what is pure, we may readily conclude that the whole nature of man is condemned by a single word. Christ therefore declares that our understanding and reason is corrupted, because it is carnal, and that all the affections of the heart are wicked and reprobate, because they too are carnal. But here it may be objected, that since the soul is not begotten by human generation, we are not born of the flesh, as to the chief part of our nature. This led many persons to imagine that not only our bodies, but our souls also, descend to us from our parents; for they thought it absurd that original sin, which has its peculiar habitation in the soul, should be conveyed from one man to all his posterity, unless all our souls proceeded from his soul as their source. And certainly, at first sight, the words of Christ appear to convey the idea, that we are flesh, because we are born of flesh. I answer, so far as relates to the words of Christ, they mean nothing else than that we are all carnal when we are born; and that as we come into this world mortal men, our nature relishes nothing but what is flesh. He simply distinguishes here between nature and the supernatural gift; for the corruption of all mankind in the person of Adam alone did not proceed from generation, but from the appointment of God, who in one man had adorned us all, and who has in him also deprived us of his gifts. Instead of saying, therefore, that each of us draws vice and corruption from his parents, it would be more correct to say that we are all alike corrupted in Adam alone, because immediately after his revolt God took away from human nature what He had bestowed upon it. Here another question arises; for it is certain that in this degenerate and corrupted nature some remnant of the gifts of God still lingers; and hence it follows that we are not in every respect corrupted. The reply is easy. The gifts which God hath left to us since the fall, if they are judged by themselves, are indeed worthy of praise; but as the contagion of wickedness is spread through every part, there will be found in us nothing that is pure and free from every defilement. That we naturally possess some knowledge of God, that some distinction between good and evil is engraven on our conscience, that our faculties are sufficient for the maintenance of the present life, that -- in short -- we are in so many ways superior to the brute beasts, that is excellent in itself, so far as it proceeds from God; but in us all these things are completely polluted, in the same manner as the wine which has been wholly infected and corrupted by the offensive taste of the vessel loses the pleasantness of its good flavor, and acquires a bitter and pernicious taste. For such knowledge of God as now remains in men is nothing else than a frightful source of idolatry and of all superstitions; the judgment exercised in choosing and distinguishing things is partly blind and foolish, partly imperfect and confused; all the industry that we possess flows into vanity and trifles; and the will itself, with furious impetuosity, rushes headlong to what is evil. Thus in the whole of our nature there remains not a drop of uprightness. Hence it is evident that we must be formed by the second birth, that we may be fitted for the kingdom of God; and the meaning of Christ's words is, that as a man is born only carnal from the womb of his mother; he must be formed anew by the Spirit, that he may begin to be spiritual. The word Spirit is used here in two senses, namely, for grace, and the effect of grace. For in the first place, Christ informs us that the Spirit of God is the only Author of a pure and upright nature, and afterwards he states, that we are spiritual, because we have been renewed by his power.

Footnotes

1 - "Monstrent bien qu'ils n'en entendent rien."

That which is born of the flesh - To show the necessity of this change, the Saviour directs the attention of Nicodemus to the natural condition of man. By "that which is born of the flesh" he evidently intends man as he is by nature, in the circumstances of his natural birth. Perhaps, also, he alludes to the question asked by Nicodemus, whether a man could be born when he was old? Jesus tells him that if this could be, it would not answer any valuable purpose; he would still have the same propensities and passions. Another change was therefore indispensable.
Is flesh - Partakes of the nature of the parent. Compare Genesis 5:3. As the parents are corrupt and sinful, so will be their descendants. See Job 14:4. And as the parents are wholly corrupt by nature, so their children will be the same. The word "flesh" here is used as meaning "corrupt, defiled, sinful." The "flesh" in the Scriptures is often used to denote the sinful propensities and passions of our nature, as those propensities are supposed to have their seat in the animal nature. "The works of the flesh are manifest, which are these: adultery, fornication, uncleanness, lasciviousness," etc., Galatians 5:19-20. See also Ephesians 2:3; 1-Peter 3:21; 1-Peter 2:18; 1-John 2:16; Romans 8:5.
Is born of the Spirit - Of the Spirit of God, or by the agency of the Holy Spirit.
Is spirit - Is spiritual, "like" the spirit, that is, holy, pure. Here we learn:
1. that all men are by nature sinful.
2. that none are renewed but by the Spirit of God. If man did the work himself, it would he still carnal and impure.
3. that the effect of the new birth is to make men holy.
4. and, that no man can have evidence that he is born again who is not holy, and just in proportion as he becomes pure in his life will be the evidence that he is born of the Spirit.

That which is born of the flesh is flesh - This is the answer to the objection made by Nicodemus in John 3:4. Can a man enter the second time into his mother's womb and be born? Our Lord here intimates that, were even this possible, it would not answer the end; for the plant will ever be of the nature of the seed that produces it - like will beget its like. The kingdom of God is spiritual and holy; and that which is born of the Spirit resembles the Spirit; for as he is who begat, so is he who is begotten of him. Therefore, the spiritual regeneration is essentially necessary, to prepare the soul for a holy and spiritual kingdom.

That which is born of the flesh is (g) flesh; and that which is born of the Spirit is spirit.
(g) That is, fleshly, namely, wholly unclean and under the wrath of God: and therefore this word "flesh" signifies the corrupt nature of man: contrary to which is the Spirit, that is, the man ingrafted into Christ through the grace of the Holy Spirit, whose nature is everlasting and immortal, though the strife of the flesh remains.

That which is born of the flesh, is flesh,.... Man by his natural birth, and as he is born according to the flesh of his natural parents, is a mere natural man; that is, he is carnal and corrupt, and cannot discern spiritual things; nor can he, as such, enter into, and inherit the kingdom of God; see 1-Corinthians 2:14. And therefore there is a necessity of his being born again, or of the grace of the Spirit, and of his becoming a spiritual man; and if he was to be, or could be born again of the flesh, or ever so many times enter into his mothers womb, and be born, was it possible, he would still be but a natural and a carnal man, and so unfit for the kingdom of God. By "flesh" here, is not meant the fleshy part of man, the body, as generated of another fleshy substance; for this is no other than what may be said of brutes; and besides, if this was the sense, "spirit", in the next clause, must mean the soul, whereas one soul is not generated from another: but by flesh is designed, the nature of man; not merely as weak and frail, but as unclean and corrupt, through sin; and which being propagated by natural generation from sinful men, cannot be otherwise; for "who can bring a clean thing out of an unclean? not one", Job 14:4. And though the soul of man is of a spiritual nature, and remains a spirit, notwithstanding the pollution of sin; yet it being defiled with the flesh, and altogether under the power and influence of the lusts of the flesh, it may well be said to be carnal or fleshly: hence "flesh", as it stands opposed to spirit, signifies the corruption of nature, Galatians 5:17; and such who are in a state of unregeneracy, are said to be after the flesh, and in the flesh, and even the mind itself is said to be carnal, Romans 8:5.
And that which is born of the Spirit, is spirit: a man that is regenerated by the Spirit of God, and the efficacy of his grace, is a spiritual man; he can discern and judge all things of a spiritual nature; he is a fit person to be admitted to spiritual ordinances and privileges; and appears to be in the spiritual kingdom of Christ; and has a right to the world of blessed spirits above; and when his body is raised a spiritual body, will be admitted in soul, body, and spirit, into the joy of his Lord. "Spirit" in the first part of this clause, signifies the Holy Spirit of God, the author of regeneration and sanctification; whence that work is called the sanctification of the Spirit, and the renewing of the Holy Ghost, 1-Peter 1:2. And "spirit", in the latter part, intends the internal work of grace upon the soul, from whence a man is denominated a spiritual man; and as a child bears the same name with its parent, so this is called by the same, as the author and efficient cause of it: and besides, it is of a spiritual nature itself, and exerts itself in spiritual acts and exercises, and directs to, and engages in spiritual things; and has its seat also in the spirit, or soul of man.

That which is born, &c.--A great universal proposition; "That which is begotten carries within itself the nature of that which begat it" [OLSHAUSEN].
flesh--Not the mere material body, but all that comes into the world by birth, the entire man; yet not humanity simply, but in its corrupted, depraved condition, in complete subjection to the law of the fall (Romans 8:1-9). So that though a man "could enter a second time into his mother's womb and be born," he would be no nearer this "new birth" than before (Job 14:4; Psalm 51:5).
is spirit--"partakes of and possesses His spiritual nature."

That which is born of the flesh is flesh - Mere flesh, void of the Spirit, yea, at enmity with it; And that which is born of the Spirit is spirit - Is spiritual, heavenly, divine, like its Author.