Is God unjust when he harden people's hearts?

God has always been selective. The blessing came through Isaac. Then the blessing came through Jacob. "Jacob I loved, Esau I hated." (Rom. 9:13) You say, "Wow, you mean God is that discriminating?" Verse 14 then says (and this is what the responder would say) "What shall we say then? Is this unjust? There is no injustice with God is there?" Mē genoito—the strongest negative in the Greek language—no, no, no, no. This isn't out of character for God to be selective. God never intended every Jew to be in the kingdom. For He says to Moses, God says, "I'll have mercy on whom I'll have mercy. I'll have compassion on whom I'll have compassion." And it doesn't depend on "the man who wills or the man who runs but on God who has mercy" (Rom. 9:15-16).

And then He goes to Pharaoh, "'For this very purpose I raised you up to demonstrate My power in you, and that My name might be proclaimed throughout the whole earth.' So then He has mercy on whom He desires and He hardens whom He desires." Wow. "You will say to me then, 'Why does he still find fault?'" How can God then find fault with us if He's the one who makes the decision? For who can resist His will? And the next verse says, shut . . . up. That's what it says in the vernacular. "On the contrary, who are you, O man, who answers back to God? The thing molded will not say to the molder, 'Why did you make me like this,' will it?" Pots don't talk back. The potter has the right over the clay. "What if God willing to demonstrate His wrath and make His power known endured with much patience vessels of wrath prepared for destruction?" (v. 22).

Do you understand that God has a right to put His wrath and His judgment and His justice and His fury on display to His own glory as much as He has a right to put His mercy and His grace on display to His own glory? Do you understand that God gets as much glory out of His wrath as He gets out of His grace? 

Paul understands that. That this is a sovereign work, and that God is not unjust. Psalm 119 says, "Your righteousness is an ever-lasting righteousness." Psalm 7:9, "You are the righteous one." God will do what God will do. Paul understands that this work of salvation is a sovereign work done by God. But then come to verse 30. "What shall we say then? Gentiles, who didn't pursue righteousness, attained righteousness."

Isn't that something? He's talking about the church, the gentile church. They were not even pursuing it, but they received it. Even the righteousness which is by what?—faith. "But Israel, pursuing a law of righteousness," that is righteousness by law, "did not arrive at that law." Why? 

Because they didn't pursue it by faith. They didn't pursue it by faith because the one in whom you must place your faith was to them a stumbling stone and a rock of offense.

So he says it's all the sovereignty of God. He hardens whom He hardens, He has mercy on whom He decides to have mercy. He loves who He loves, He hates who He hates. 

But Israel didn't receive the imputed righteousness of God because they sought it by law and not by faith in Christ. They're fully responsible for pursuing righteousness in a false way, and denying righteousness in the only way that it can ever come to the sinner, through faith in Christ. Author: RC Sproul