“But though he had done so many miracles before them, yet they believed not on him” (Jn 12:37).

The following is an excerpt from “The Matthew Henry Study Bible”.

12:37 yet they believed not: The most plentiful and powerful means of conviction will not will not of themselves work faith in the depraved prejudiced hearts of men.  These saw, and yet believed not.

12:38-40 could not believe: They could not believe, that is, would not.  They were obstinately resolved in their infidelity.  He hath blinded their eyes: it is certain that God is not the author of sin, and yet there is a righteous hand of God sometimes to be acknowledged in the blindness and obstinance of those who persist in impenitence and unbelief by which they are justly punished for their resistance and rebellion against the divine law.  heal them: Observe the method of conversion implied here, and the steps taken in it: (1) Sinners are brought to see with their eyes, to discern the reality of divine things and to have some knowledge of them. (2) To understand with their heart, to apply these things to themselves, not only to assent and approve, but to consent and accept.  (3) To be converted and effectually turned from sin to Christ, from the world and the flesh to God, as their felicity and portion.  Then God will heal them, will justify and sanctify them, will pardon their sins.  What God has foretold will certainly come to pass, and so, by a necessary consequence, it might be said that therefore they could not believe because God by the prophets had foretold they would not”.

Henry, M. 1997, “The Matthew Henry Study Bible: King James Version”, copyright Thomas Nelson Inc., pub Hendrickson Publishers, Peabody, MA.