8 Then I heard the voice of the Lord saying,
"Whom shall I send? And who will go for us?"
And I said, "Here am I. Send me!"
9 He said, "Go and tell this people:
"‘Be ever hearing, but never understanding;
be ever seeing, but never perceiving.’
10 Make the heart of this people calloused;
make their ears dull and close their eyes.
Otherwise they might see with their eyes, hear with their ears,
understand with their hearts, and turn and be healed."
With respect to their not understanding the parables:Even in these applications of the verses there is diversity. For Jesus at times spoke in a manner to the general public in which it took some intuition to understand and one must interpret his sayings in the right sense. But if one doesn't listen in the right spirit, then Jesus' teachings may be difficult to understand and thus is born cults and such. But the point is that Jesus make some effort to keep people in the dark. John 12:40 is another example for it is preceded by the following:
Matthew 13:15 For this people’s heart has become calloused; they hardly hear with their ears, and they have closed their eyes. Otherwise they might see with their eyes, hear with their ears, understand with their hearts and turn, and I would heal them.’
Mark 4:12 so that, "‘they may be ever seeing but never perceiving, and ever hearing but never understanding; otherwise they might turn and be forgiven!’"
Luke 8:10 He said, "The knowledge of the secrets of the kingdom of God has been given to you, but to others I speak in parables, so that, "‘though seeing, they may not see; though hearing, they may not understand.’
With respect to not recognizing Jesus despite his miracles
John 12:40 "He has blinded their eyes and deadened their hearts, so they can neither see with their eyes, nor understand with their hearts, nor turn— and I would heal them."
With respect to Paul's experience with the Jews in Rome not comprehending the gospel even after a lengthy presentation
Acts 28:27 For this people’s heart has become calloused; they hardly hear with their ears, and they have closed their eyes. Otherwise they might see with their eyes, hear with their ears, understand with their hearts and turn, and I would heal them.’
12:34 The crowd spoke up, "We have heard from the Law that the Christ will remain forever, so how can you say, ‘The Son of Man must be lifted up’? Who is this ‘Son of Man’?"Notice how Jesus kept them in the dark in a sense even though speaking of putting their trust in the light. For he was not clarifying his meaning. But what he said was clear enough for the elect. Jesus said, "For judgment I have come into this world, so that the blind will see and those who see will become blind." John 9:39 Those who reckoned they could see were the Jews who rejected Christ, just as many religious people today do not believe in Jesus as the Son of God. They are in actuality blind, but their blindness was not fully evident until they were presented with Jesus. So also there are religious people today who reckon themselves righteous, but present them with Jesus and his teachings and they explode.
35 Then Jesus told them, "You are going to have the light just a little while longer. Walk while you have the light, before darkness overtakes you. The man who walks in the dark does not know where he is going.
36 Put your trust in the light while you have it, so that you may become sons of light." When he had finished speaking, Jesus left and hid himself from them.
37 Even after Jesus had done all these miraculous signs in their presence, they still would not believe in him.
In contrast to Jesus it appears that Paul tried to lay out the gospel very clearly but, though being a Jew himself, the Jews generally did not seem to be able to comprehend the gospel.
What's the Application?
Whether we conclude that Isaiah 6:9,10 was applied in a causative sense with respect to the presentation of the gospel to the Jews by presenting it in an obscure and intuitive manner, or whether it is predictive being descriptive of the blindness and hardness of heart of such people against the gospel, the question we're faced today is how does it apply in evangelism today. For example does it apply to the Gentiles? I don't think so for notice the context of Paul's statement in Acts 28:
27 For this people’s heart has become calloused; they hardly hear with their ears, and they have closed their eyes. Otherwise they might see with their eyes, hear with their ears, understand with their hearts and turn, and I would heal them.’And so we see today that while the church start out primarly Jews as were the apostles, it is dominated by Gentiles who were reckoned blind but now see. The Jews today except for a small minority are blind to the gospel.
28 "Therefore I want you to know that God’s salvation has been sent to the Gentiles, and they will listen!"
Romans 11:7,8 "What then? What Israel sought so earnestly it did not obtain, but the elect did. The others were hardened, as it is written: "God gave them a spirit of stupor, eyes so that they could not see and ears so that they could not hear, to this very day." (Isaiah 29:10)
Why did God harden their hearts?
It seems the principle here that God had hardened their hearts after a long time of willful disobedience. We see this principle also in Romans 1 where it speaks of God giving people over to their sinfulness. And even Christians are warned, "encourage one another daily, as long as it is called Today, so that none of you may be hardened by sin’s deceitfulness." Hebrews 3:13
But why did God send Isaiah preach to those who couldn't hear?
Because sometimes things have to be said regardless of how people may react. The prophets primary duty is to tell the truth. Influencing people to change their minds is secondary. Notice that much as Jesus ministry was one of grace, he also practiced prophecy in this sense as well:
Matthew 23:20-35Rather than bring people to repentance, this kind of rhetoric got him crucified. As we walk as Christ walked this type of rhetoric should also be considered a legitimate part of our ministry. I say this in contrast to some Christian's obsessive concern over "turning people off". Turning people on to Christ is not the main objective of evangelism.
"Woe to you, teachers of the law and Pharisees, you hypocrites! You build tombs for the prophets and decorate the graves of the righteous. And you say, ‘If we had lived in the days of our forefathers, we would not have taken part with them in shedding the blood of the prophets.’ So you testify against yourselves that you are the descendants of those who murdered the prophets. Fill up, then, the measure of the sin of your forefathers! "You snakes! You brood of vipers! How will you escape being condemned to hell? Therefore I am sending you prophets and wise men and teachers. Some of them you will kill and crucify; others you will flog in your synagogues and pursue from town to town. And so upon you will come all the righteous blood that has been shed on earth, from the blood of righteous Abel to the blood of Zechariah son of Berekiah, whom you murdered between the temple and the altar."