7 What then? Israel has not obtained what it seeks; but the elect have obtained it, and the rest were blinded.
and the rest [non-believers] were blinded [caused to be hardened].
The “rest” is the bulk of the nation Israel. The “elect” were those who accepted salvation by grace through faith, but most of nation went negative toward grace.
Paul explained in the following verses from quotations what he meant by hardening. The upshot of those who do not accept the grace way of salvation is that God will allow them to harden their hearts.
Ro 11:25, For I do not desire, brethren, that you should be ignorant of this mystery, lest you should be wise in your own opinion, that blindness in part has happened to Israel until the fullness of the Gentiles has come in.
“Blinded” is the Greek word for hardened. This word means to petrify, to calcify. Here the hardening is an attitude of negative response toward God’s grace provision. These people were blind to salvation by grace.
The blindness or hardening was an act of God for judgment on Israel. Beginning with the next verse, Paul began to quote verses to demonstrate that God was the source of their hardness of heart (Deut 29:4; Isa 6:9). God hardens those who harden themselves.
God is the source of the hardening (passive voice). God did the hardening but the people did the stumbling over the message (11:11). God hardened them because they rejected His message. In spite of the rejection of grace by the bulk of Israel, God will gather to Himself a remnant out of hardened Israel.
God hardened Pharaoh’s heart, but not until Pharaoh first hardened his own heart. God made his heart harder by placing events in his life that forced him to make yet further negative decisions toward God. The greater Pharaoh’s rebellion, the harder his heart became. The more Israel rejected the will of God, the harder their hearts became.
The hardening here is the effect, not the cause. The cause of their hard heart was their belief that self-righteousness was the means of salvation (Ro 9:31-33). God does not harden people arbitrarily or maliciously. He only does this when there is obstinate, willful departure from salvation by grace.
God’s hardening of Israel has to do with His permission of free moral agency. There is a point where God takes off the restraint of human negative attitude toward grace. He did that to Pharaoh. The more God revealed His power, the greater was Pharaoh’s resistance to God’s plan.
It is important to note that the hardening is not necessarily final. It is possible for some to repent of their persistent trust in self-righteousness. There is hope even for those who harden themselves (11:25). A remnant opened themselves to God’s plan of salvation by grace. The elect obtained salvation by faith, whereas the “rest” hardened their hearts towards salvation by grace.
Jesus quoted Isaiah 6 to demonstrate this same point:-
John 12:40, “He has blinded their eyes and hardened their hearts, Lest they should see with their eyes, Lest they should understand with their hearts and turn, So that I should heal them.”
Light rejected blinds the heart further.
God hardens those who harden themselves. Deepening apostasy produces increasing inability to grasp the seriousness of the direction of salvation by works. God will permanently bind people to their ultimate decision to reject salvation by grace.
The “soulish man” thinks that God’s truth is “foolishness” (1 Co 2:14). However, some will respond to God’s initiative (1 Co 2). God will actively harden those who go negative toward grace. Without God drawing people to Himself, there is no chance of them coming to Christ.
As Israel failed to obtain what she sought, so people today dabble in Christianity without truly accepting salvation by grace. It is possible to admire food without eating it. There are people who believe that Jesus was an excellent person, but they will not accept the fact that He died for their sins. They will not embrace the idea that Jesus fulfilled every claim of divine judgment on them.