Let's begin with verse 6: "They are not all Israel who are descended from Israel." This is the theme that Paul develops in the rest of the chapter. As Paul continues in verse 7, "nor are they all children because they are descendants of Abraham, but 'in Isaac shall your descendants be called.'" He explains that statement in verse 8: "So, those who are the children of the flesh are not the children of God, but the children of the promise are counted as descendants." Paul goes on to demonstrate this from the comparison of Jacob and Esau, the twin sons of Isaac. But I would also add what Genesis says about Ishmael. In Genesis 17:18-19, Abraham prays to God, "Oh that Ishmael might live before You!" Yet, God replies, "No." Not "maybe," not "let's hope so." Rather, His answer is a straightforward and unconditional refusal. That is a demonstration of reprobation, which is the flip side of election. Just as God chose some for salvation, He also chose others for condemnation. More of that to come.
Paul reminds us of Isaac's twin sons, Jacob and Esau (v. 10). Then he begins their story (verses 11-13): "though they were not yet born and had done nothing either good or bad—in order that God’s purpose of election might continue, not because of works but because of Him who calls— she was told, 'The older will serve the younger.' As it is written, 'Jacob I loved, but Esau I hated.'" Before the twins were even born or had committed any personal sins, God had decreed in His sovereignty that Jacob would be preferred over Esau, the second-born over the firstborn, contrary to the custom, because He had already declared, "Jacob I loved, but Esau I hated" (quoted from Malachi 1:2-3). God explicitly states that His purpose was to demonstrate His sovereign election, to exclude any merit in either child (or, by extension, in any of us).
Among Americans, the nearly-universal reaction to that is, "But that's not fair!" The same response is made by a hypothetical audience in verse 14. In response, Paul quotes (v. 15, from Ex.33:19): "I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion!" Note that He makes no effort to explain that it is fair. Rather, He claims that we are in rebellion even to ask the question! Verse 20, "Who are you, O man, to answer back to God?" As Creator, He rules over His creations! Verse 21, "Has the potter no right over the clay, to make out of the same lump one vessel for honorable use and another for dishonorable use?" Here He addresses the two doctrines of unconditional election and reprobation together. They are actions consistent with His place as sovereign creator and sustainer of all things. He doesn't answer our concerns about fairness because those concerns are illegitimate expressions of rebellion!
He endures these "vessels of wrath prepared for destruction" (v. 22) "in order to make known the riches of his glory for vessels of mercy, which he has prepared beforehand for glory." He uses the one, the objects of His wrath, to provide a contrast to the objects of His mercy, that He may reveal Himself, both in His justice and His mercy. The doctrines of grace are all about Him, not us.
As a Gentile, I am especially blessed by God's sovereign grace, for those He has prepared for glory include "even us whom He has called, not from the Jews only but also from the Gentiles" (v. 24). As He prophesied in Hosea 2:23-24, "Those who were not My people I will call 'My people,' and her who was not beloved I will call 'beloved.' And in the very place where it was said to them, 'You are not My people,' there they will be called 'sons of the living God.'" My ancestors are those described by Paul in Ephesians 2:11-22, who had no hope and were without God in our world, but now are fellow citizens with the saints. If it hadn't been for the sovereign grace of God, there is no human way that the Gospel would have entered my life, that I could be born again by the Holy Spirit.
And that is true of everyone who is reading this post. Whether you are nodding your head in agreement or purple-faced with rage, you could never have known Jesus Christ as savior without the truths of the doctrines of grace. Yes, even Arminians are saved by sovereign grace!