What does John 9:8 mean?
Jesus has just given eyesight to a man who was born blind—a powerful metaphor for how God grants faith and belief to those who would otherwise never have it. This incident included Jesus' explanation that not all suffering is caused by the hurting person's own sin (John 9:1–4). Jesus also breached the Pharisee's traditions by not only healing on the Sabbath (John 9:14), but by mixing clay (John 9:6): a crime according to their oral laws.When Jesus healed the lame man at the Pool of Siloam (John 5:1–9), His subject would have been well-known for his condition. It was not some unknown, possibly staged actor. Here, the same idea is true. This man's lifelong blindness was common knowledge, removing any possibility of this being a mere trick. The questions raised about this man's identity are not all expressions of doubt—they're mostly declarations of surprise. The people know exactly who this man is, and precisely what his problem was. For that specific person to suddenly have sight is a shocking experience.
Of course, as in all cases, there will be hardened skeptics. As shown in the next verse, some in the crowd try to explain away the miracle by suggesting that this is not actually the blind beggar, but an uncanny lookalike. Despite the man's own claims, and the witness of the crowd, there were those who chose not to accept the evidence of a miracle. This is a common occurrence, even today, and another example of why "show me a miracle and I'll believe" is not an honest response to the gospel.