The People of God
"As indeed he says in Hosea, '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.'"
God's election to salvation and His reprobation to punishment are parallel but not equivalent. Most significantly, because the elect and the reprobate come from the same lump of fallen clay (Rom. 9:21), the Lord in effecting salvation must work against sinners' natural inclinations. On the other hand, fallen people oppose the Lord by nature, so in reprobation He needs only to leave them alone. Therefore, we say that God passes over the reprobate, leaving them in sin, or that He permits the reprobate to remain in their existing condition. Still, as John Calvin said, God does not give "bare" permission, for He ordains all things. The Lord has no moral responsibility for damnation and does not work in it the same way He works in salvation, but He does not passively observe His creation either.
The objections to the Lord's hardening of Pharaoh that the Apostle anticipates and answers show us that he is not talking about mere permission (v. 19). Few would object that it is "unfair" for God to allow sinners to choose their own damnation as long as His permission does not guarantee their choice. After all, we give people under our charge the freedom to make choices—even wrong choices—knowing that if they make the wrong decisions, our permission will not have made their choices certain. Yet God's permission guarantees the outcome He has ordained, though He remains blameless when people, having been permitted to do evil, commit sin. That raises questions about the Lord's justice, but Paul's only answer is that we may not believe our Creator is unjust in this matter (vv. 20-21). By faith we continue to believe that God is just even when He has not explained Himself fully to us.
God does not tell us what motivates His election and reprobation in specific cases—we do not know why He saves Alice but passes over Suzie. But He does tell us the elect and reprobate exist to show forth the riches of His glory (vv. 22-23). In passing by some for salvation, He reveals His just wrath against sin and His power. In saving the undeserving, He shows His mercy on sinners and His tremendous love in adopting for Himself a people who by nature are not His people. Without the dual reality of predestination to salvation and reprobation unto damnation, we would not see the fullness of God's attributes and disposition. The Lord shows forth the glory of His character in saving some and condemning others, and this is to be praised because His glory is the highest good of all.
Coram Deo
God chooses us for His glory and not on account of any good in us. John Calvin comments that God's glory is revealed in destroying the reprobate, because the only thing that separates the elect from the reprobate is that the elect "are delivered by the Lord from the same gulf of destruction [as the reprobate] . . . by no merit of their own, but through his gratuitous kindness." Let God's elect—those who persevere in faith—remember this and learn humility.