Though the Lord elects some unto life by His free mercy, He likewise passes over others, leaving them in their guilt and corruption, not by putting evil into them, but by withholding the grace by which their hearts might be softened. This permission avoids God being the author of evil. He permits it, but it does not emanate from him. Man is a child of wrath already, and election unto salvation is a positive active decree. There is no need for a negative decree unto reprobation. This “passing over” is the lack of a positive decree unto special election. He leaves the reprobate to his sin.
Deuteronomy 29:4 “But to this day the LORD has not given you a heart to understand or eyes to see or ears to hear.” God withholds grace here. Romans 9:18 “So then he has mercy on whomever he wills, and he hardens whomever he wills.” The mercy is active; the non-mercy is passive but sovereign. Romans 11:7 “The elect obtained it, but the rest were hardened.” A plain distinction: God gives to some; He does not give to others.
God “gives them up” by not restraining their corruption. Romans 1:24, 26, 28 “God gave them up… God gave them up… God gave them over…” This is not God creating evil in them, but withdrawing His restraining grace.
God permits but also sovereignly ordains the state of the wicked. Psalm 81:11–12 “So I gave them over to their stubborn hearts, to follow their own counsels.” He leaves them to themselves… this is the passive decree. God hides truth from some while revealing it to others. This is not an active decree, but a passive / permission by not actively decreeing an action: Matthew 11:25–26 “You have hidden these things from the wise and understanding and revealed them to little children… such was your gracious will.” Hiding is passive, revealing is active.
By passing by those whom he wills, and by choosing others, God manifests his free election; for when others are not elected, it is because God has willed to leave them in their miserable condition, and this is the cause why their destruction is certain and inevitable.
In all of this, God is not unfair.