Even though He had performed so many signs in their presence, they did not believe in Him.
References for John 12:37
But this was to fulfill the word of Isaiah the prophet, who said: Lord, who has believed our message? And who has the arm of the Lord been revealed to?
References for John 12:38
This is why they were unable to believe, because Isaiah also said:
He has blinded their eyes and hardened their hearts, so that they would not see with their eyes or understand with their hearts, and be converted, and I would heal them.
References for John 12:40
Isaiah said these things because he saw His glory and spoke about Him.
References for John 12:41
Nevertheless, many did believe in Him even among the rulers, but because of the Pharisees they did not confess Him, so they would not be banned from the synagogue.
For they loved praise from men more than praise from God.
References for John 12:43