John 12:39
Isaiah revealed the reason they could not believe:
John 5:44
How can you believe? You seek praise and glory from one another? Why do you not seek the glory that comes from the only God?
Isaiah 6:9-10
He said: Go and tell this people: 'Hear constantly but do not understand. See constantly but do not perceive.'
Isaiah 44:18-20
They do not know or understand anything. Their eyes are plastered shut and cannot see. Their minds are closed and therefore they cannot understand.
John 6:44
No man can come to me unless the Father, who sent me, draws him. I will resurrect him (raise him up) in the last day.
John 10:38
But if I do them and you do not believe me, believe the works! That way you may know and understand that the Father is with me, and I am with the Father.
2 Peter 2:14
They have eyes full of adultery that cannot cease from sin! They entice unsteady persons. Their hearts are full of covetousness. They are children of cursing.