(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?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.