Jesus comes doing ONLY good — restoring sight, restoring limbs, restoring life itself — but some still can’t see him for who he is, which John reiterates quite starkly in verses 39-40. The miracle that should have made a believer out of anyone is that which further fixes some people in their unbelief. They want Jesus dead, along with Lazarus (again). God the Father himself speaks aloud to the onlookers, confirming Jesus is the Christ, but they attribute it to thunder and angels.
This is a strange comfort when I think of the people in my life who can’t see Jesus for who he is. Even when he was here on earth, working miracles before men’s very eyes, some remained blind. But those to whom Jesus gave sight, they truly saw, truly believed, and were truly saved. Nothing has changed. He still must open eyes.