(33) If this man were not of God.—His argument meets each of their assertions. His general assumption, admitted as a universal truth (John 9:31), had denied their assertion that this Man was a sinner. His conclusion now denies their assertion, “This Man is not of God” (John 9:16).

He could do nothing—i.e., nothing of this kind, no miracle such as this, much less this miracle itself.

9:24-34 As Christ's mercies are most valued by those who have felt the want of them, that have been blind, and now see; so the most powerful and lasting affections to Christ, arise from actual knowledge of him. In the work of grace in the soul, though we cannot tell when, and how, and by what steps the blessed change was wrought, yet we may take the comfort, if we can say, through grace, Whereas I was blind, now I see. I did live a worldly, sensual life, but, thanks be to God, it is now otherwise with me, Eph 5:8. The unbelief of those who enjoy the means of knowledge and conviction, is indeed marvellous. All who have felt the power and grace of the Lord Jesus, wonder at the wilfulness of others who reject him. He argues strongly against them, not only that Jesus was not a sinner, but that he was of God. We may each of us know by this, whether we are of God or not. What do we? What do we for God? What do we for our souls? What do we more than others?Could do nothing - Could do no such work as this. This reasoning was conclusive. The fact that Jesus could perform miracles like this was full proof that he was commissioned by God - proof that never has been and never can be refuted. One such miracle proves that he was from God. But Jesus gave many similar proofs, and thus put his divine mission beyond the possibility of doubt. 31. they cast him out—judicially, no doubt, as well in fact. The allusion to his being "born in sins" seems a tacit admission of his being blind from birth—the very thing they had been so unwilling to own. But rage and enmity to truth are seldom consistent in their outbreaks. The friends of this excommunicated youth, crowding around him with their sympathy, would probably express surprise that One who could work such a cure should be unable to protect his patient from the persecution it had raised against him, or should possess the power without using it. Nor would it be strange if such thoughts should arise in the youth's own mind. But if they did, it is certain, from what follows, that they made no lodgment there, conscious as he was that "whereas he was blind, now he saw," and satisfied that if his Benefactor "were not of God, He could do nothing" (Joh 9:33). There was a word for him too, which, if whispered in his ear from the oracles of God, would seem expressly designed to describe his case, and prepare him for the coming interview with his gracious Friend. "Hear the word of the Lord, ye that tremble at His word. Your brethren that hated you, that cast you out for My name's sake, said, Let the Lord be glorified; BUT He shall appear to your joy, and they shall be ashamed" (Isa 66:5). But how was He engaged to whom such noble testimony had been given, and for whom such persecution had been borne? Uttering, perhaps, in secret, "with strong crying and tears," the words of the prophetic psalm, "Let not them that wait on Thee, O Lord God of hosts, be ashamed for my sake; let none that seek Thee be confounded for my sake, O God of Israel; because for Thy sake I have borne reproach … and the reproaches of them that reproached Thee are fallen upon me" (Ps 69:6, 7, 9). If therefore this man (for still he apprehended him no more) had not some special authority from God, and there were not some special presence of God with him, he could do nothing that is of this nature. It is a work beyond the power of man, and beyond that power first we read God did ever trust any man with.

If this man were not of God,.... If he had not his mission, commission, and credentials from God; if he had not been sent by him, and had not authority from him, and was not assisted by him, as man, or God was not with him,

he could do nothing; or "not do these things", as the Syriac version reads; that is, such miraculous works; or, as the Persic version, "he could not do this miracle": open the eyes of a man born blind. His doing this is a full proof that he is of God, and comes from him.

If this man were not of God, he could do nothing.