Insincere Questions

25 He answered, “Whether he is a sinner I do not know. One thing I do know, that though I was blind, now I see.” 26 They said to him, “What did He do to you? How did He open your eyes?” 27 He answered them, “I have told you already, and you would not listen. Why do you want to hear it again? Do you also want to become His disciples?” (John 9:25–27 ESV) 

The healed man, unlike his parents, did not give in to evasion out of fear for the religious leaders. The man said "I do not know" out of a genuine lack of knowledge concerning Jesus' identity. For all the healed man knew, Jesus may have been merely a human prophet and thus–strictly speaking–a sinner, like all men. As seen in subsequent verses, the man doubts Jesus is a sinner in the way His accusers mean. The accusatory religious leaders ask for the healed man's account again, not as a genuine question, but as a means of intimidating the man, hoping he will change his story. The man sees through their tactic and asks a question of his own. The answer to the healed man's question should have been a genuine "yes".