What does John 9:17 mean?

The Pharisees are interrogating a beggar who was born blind (John 9:1–2), but now is able to see thanks to a miraculous intervention by Jesus (John 9:6–7). These supernatural actions are intended to prove that Jesus is, in fact, divine, and is the Promised One predicted by Scripture. In fact, the Old Testament specifically refers to restoring the sight of the blind as part of the Messiah's ability (Isaiah 29:18; 35:5; 42:7). Unfortunately, the Pharisees are more concerned with their own traditions and interpretations than obvious evidence. Among their most sacred beliefs is a strict approach to the Sabbath. Jesus' miracle not only occurred on this day (John 9:14), it involved making clay, which oral traditions specifically forbade on the Sabbath, as a form of work. Many of the Pharisees, despite the miracle, refuse to believe that a man who does not accept their traditions can be from God (John 9:16).

At this point, the interrogators continue to press the formerly blind man for answers. Throughout this story, the once-blind man is consistent, sincere, and honest. He does not pretend to know anything other than what has actually happened. His conclusion, stated here, is common sense. Jesus has done something profoundly good, and supernaturally powerful. Therefore, the man believes that Jesus is "a prophet." Since he hasn't actually seen or spoken to Jesus since being told to wash mud off of his then-still-blind eyes (John 9:11–12), this is as much as he can really assume.

What happens next proves how hard-headed and stubborn religious skeptics can be. People in the crowd realize this is a man who was born blind (John 9:8–9). Even those who doubt have to admit that he certainly looks like the same person—suggesting some explanation other than a miracle. The Pharisees, on the other hand, are so cynical that they want to interview the man's parents, just to confirm that this is, in fact, the same beggar everyone recognizes!