Before we leave this difficult passage about God hardening hearts and blinding eyes, we need to address the phrase, “lest they should understand with their hearts and turn, so that I should heal them” (John 12:40). Why would God be upset if they would repent and he heal them? Isn’t God interested in all coming to repentance? (2 Peter 3:9). Yes, that is why I do not believe he is speaking of individuals. He is speaking of the Nation as a whole.
This passage is better understood when we read Romans 11:25-32. I encourage you to read the entire passage. But in summary, the Nation of Israel was blind to who Jesus was so that the message would be taken to the Gentiles. But God will not leave them blind (Romans 11:31). God teaches both Jews and Gentiles that we all need his mercy.
And what we need, he supplies (Jeremiah 9:24).
