The Jews still did not believe that the man had been blind and had received his sight until they summoned his parents
18. But the Jews did not believe. There are two things here which ought to be observed; that they do not believe that a miracle has been performed, and that, being wilfully blinded through a perverse hatred of Christ, they do not perceive what is manifest. The Evangelist tells us that they did not believe. If the reason be asked, there can be no doubt that their blindness was voluntary.
One would have expected that such a miracle as Christ wrought upon the blind man would have settled his reputation, and silenced and shamed all opposition, but it had the contrary effect; instead of being embraced as a prophet for it, he is prosecuted as a criminal. I.
Commenting on John 9:13-34
But the Jews did not believe concerning him,.... Not Jesus, but the blind man; that he had been blind, and received his sight; they imagine there was a fraud in the case, that it was collusion between Jesus and this man; that he was a man who had never been blind, but only had given out that he was, and pretended he had now received...