Introduction:
You have heard this stated a number of times before, but it is the kind of truth that all of us need to hear again and again. “Finally, my brothers, rejoice in the Lord. to write the same things to you is no trouble to me and is safe for you” (Philippians 3:1, ESV). And so here it is: Hard teaching creates soft hearts, and soft teaching creates hard hearts. Calvinism is hard doctrine, but it is supposed to be hard doctrine for the tenderhearted—not hard doctrine to match the hearts. 
The Text:
“It was said unto her, The elder shall serve the younger. As it is written, Jacob have I loved, but Esau have I hated. What shall we say then? Is there unrighteousness with God? God forbid. For he saith to Moses, I will have mercy on whom I will have mercy, and I will have compassion on whom I will have compassion. So then it is not of him that willeth, nor of him that runneth, but of God that sheweth mercy” (Romans 9:12–16).
Summary of the Text:
When Rebekah went to an oracle about the conflict that was happening in her womb, she was told that, of the twins, the older would serve the younger (v. 12; Gen. 25:23). This was reinforced centuries later, at the other end of the Old Testament, when Malachi said that God loved Jacob, but hated Esau (v. 13; Mal. 1:2-3). Keep in mind that Jacob here refers to the Jews, and Esau refers to the nation of Edom. But to take this up to a larger scale doesn’t really solve any of our ruffled-free-will-feather problems. If you were a devotee of free will, would you feel better if somebody told you that God had only predestined that the airliner would crash, not that the passengers would? Now when we are told that God loved Jacob and hated Esau, our natural (fleshly) reaction is to charge God with unrighteousness. And so Paul raises the question. Is there unrighteousness with God (v. 14)? It cannot be. God forbid. No way. And what is the reason given for denying unrighteousness with God? The reason is what God said to Moses when Moses begged to see His glory (Ex. 33:19). God will be gracious to whom He pleases. He will be merciful to whom He pleases (v. 15). Grace is grace, and mercy is mercy. Neither of them can be earned or merited—not a scintilla of merit anywhere in it. So then, we come to the hard conclusion that, rightly understood, hard grace creates tender hearts. But in order to be hard grace, it must be not dependent upon the will of man, or the running of man, but rather upon the mercy of God alone (v. 16).
No, Really, Not a Scintilla:
The heart of man can manufacture merit—something that he can use to argue that God is somehow obligated or required to show mercy—out of virtually anything. It is our knock-off of creatio ex nihilo. One of our favorite arguments arises from any mercy shown to others. Because our hearts are naturally envious, this argument seems compelling to us. What God gives to one, He must give the same thing to all others. But grace, by definition, cannot be demanded. For any reason.
Suppose there were two men on death row, and both of them richly deserve to be there. Each one was about as foul as a human being can get. Now also suppose that the governor pardons one of them, and does so for good reason. But that good reason has nothing to do with the worthiness of the one pardoned. It was dirty dozen mission or something. Now here is the question. Has the governor in any way wronged the convict that he did not pardon? Is that convict getting anything but what he deserves? He is getting nothing but justice, while the other is getting nothing but mercy. And mercy to one does not create any obligation within God toward the other. It is not of him who wills, or of him who runs, but of God who shows mercy.
Hard Grace:
We do not insist on these doctrines of hard grace because we have an emotional need that somebody be damned. Rather, we insist upon it because we want to remember that grace is infinite grace. When God saved me, and when God saved you, He was under absolutely no external obligation to do so. Our need did not create His obligation—His love created the obligation. Our need was made up of our rebellion, our selfishness, our pettiness, our insolence, and our pride. In short, God could have refused to save you, He could have passed you by as He has in fact passed by many others, and He would not have been an iota less gracious. His infinite holiness would not have been diminished at all if the number of the elect had been diminished by one. Subtract me from that throng in front of the throne of God, and the saints would still be able to sing, “Salvation to our God which sitteth upon the throne, and unto the Lamb” (Rev. 7:10). So walk through that multitude, and you will not be able to find one person who deserves to be there.
Nature and Extent:
Now why emphasize this? Before we consider the extent of God’s grace, we have to anchor the nature of grace in our hearts and minds. That is because if we do not do this, we will draw false and destructive inferences about grace from the glorious extent of it. This is a filthy, undeserving, rebellious and insolent world—and it will be gloriously saved.
“All the ends of the world shall remember and turn unto the Lord: And all the kindreds of the nations shall worship before thee” (Ps. 22:27).
“The Lord said unto my Lord, Sit thou at my right hand, Until I make thine enemies thy footstool” (Ps. 110:1).
“For the earth shall be filled with the knowledge of the glory of the Lord, As the waters cover the sea.” (Hab. 2:14).
“For God sent not his Son into the world to condemn the world; but that the world through him might be saved” (John 3:17).
“And again, Esaias saith, There shall be a root of Jesse, and he that shall rise to reign over the Gentiles; in him shall the Gentiles trust” (Rom. 15:12).
And all of it grace, all of it mercy, all of it Christ.