[Jesus Christ] passed by, he saw a man blind from birth.
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Having said these things, he spit on the ground and made mud with the saliva. Then he anointed the man's eyes with the mud and said to him, "Go, wash in the pool of Siloam" (which means Sent). So he went and washed and came back seeing.
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Many of them said, "He has a demon, and is insane; why listen to him?" Others said, "These are not the words of one who is oppressed by a demon. Can a demon open the eyes of the blind?"

The Jews had certain acts that the coming Messiah would need to perform to prove his divinity, not that Christ Jesus was required to do so. In this case, Jesus heals a man born blind, something the Jews could not do, and never had seen done. He also uses a forbidden method; and a method that, in the eyes of the Jews could not work! Notwithstanding, the leaders reject Jesus, and the people soon follow, and for this national Israel was punished in 70 AD and scattered across the face of the planet (See Mattew for 24 for specific details). Some recognised the truth of the miracle, to paraphrase; can this man have a demon and do these things, recognising the Pharisees' own writings, that only Messiah could do such a thing.