Light and darkness, sight and blindness are metaphors that Jesus uses to show whether or not people are "getting it". In the story of the man born blind John contrasts the physical blindness and now sightedness of the unnamed man with the physical sightedness and spiritual blindness of the religious leaders. Spiritual blindness is a consistent theme in the gospels. Jesus welcomes and encourages those who know they are in darkness. He challenges and castigates those who, though claiming to be in the light are, in fact, walking in darkness. To put it another way, Jesus generally only has trouble with those who insist they have it all figured out. Doubt and asking questions is not the enemy of faith -- fear is.
For the religious mind, being right trumps all other options. The state of a person, his/her potential salvation, their gifts, etc. are secondary. Jesus deals with individuals and leads them out of darkness and into light. The simple responses of the man born blind become increasingly infuriating to the Pharisees. I watched an old Steve Martin film called "Leap of Faith" over the weekend. Martin plays a corrupt and crooked traveling "evangelist" who makes no bones about the fact that he is in it for the money and has no faith of his own. In the film there is an authentic healing and Martin's character is flabbergasted and angry. The authentic healing of the man born blind calls into question all of their assumptions. The worse thing in the world for the religious (or the huckster) is to come face to face with the real thing. When we are AUTHENTIC followers of Christ and not just putting on the face, the talk and the correct view points, the world notices and comes to look.
The end of the story contains a significant moment. In verse 38 it says "He said, "Lord, I believe." And he worshiped him. This is the first instance of someone "worshiping Jesus" in John's gospel. We have, up to this point, see people call Jesus "Son of God" and have acknowledged his divinity (John 6: You are the Christ, son of the Living God!). Verse 38 is the first instance of someone acting on that understanding and offering to Jesus worship.