What does John 9:35 mean?
The man Jesus healed of lifelong blindness has been excommunicated by the scribes and Pharisees (John 9:22, 34). Beyond his support for Jesus (John 9:25), this man also embarrassed local religious leaders by exposing their hypocrisy. Though he knew little about the man who healed him, this formerly-blind beggar knew more than enough to recognize a messenger of God (John 9:30–33). His challenge to the religious leaders earned him their insults and hatred (John 9:28, 34).Prior to this moment, this man has not actually "seen" Jesus. His blindness was healed when he obeyed Jesus' command to wash off his eyes (John 9:6–7); Jesus was not there when the beggar gained eyesight. Now, Jesus finds the man after his run-in with the scribes and Pharisees.
As He often does, Jesus challenges the man by asking him to explain his own beliefs. This question is important for several reasons. Jewish people associated the term "Son of Man" closely with the Messiah (Daniel 7:13; 9:25). To this point, the healed man has not said he thinks Jesus is the Messiah, only that he believes Jesus has been sent by God (John 9:11, 17, 33).
As the following verses show, this once-blind man is more than willing to follow what he has learned from his experiences; he only needs to be told how (Matthew 7:7).