What does John 9:22 mean?

This verse is often presented in parentheses, since it's a footnote inserted by John into the story. After Jesus healed a man born blind, local religious leaders began to interrogate the healed man's parents. Their answers, given in the prior verses, are brief, fact-based, and clearly show that these people want no part of this controversy. In modern speech, they seem to be saying, "he's our son, who was born blind—other than that, we have no comment."

"The Jews"—John's term for the religious leaders of Jerusalem and their followers—have asked repetitive questions about this miraculous incident. They often ask "who" has done it, in part to see if people are going to identify Jesus as the Messiah. They also ask "how" the miracle was done. They refuse to believe that Jesus is the Promised One, so these scribes and Pharisees looks for any other explanation for what has occurred.

This verse explains why the once-blind man's parents are so timid. The religious leaders of Jerusalem have made up their minds—therefore, they promise to excommunicate anyone who thought Jesus was the Messiah. These parents are making a conscious effort to avoid that kind of trouble.