How do we know that God has mercy on whom He chooses?

The doctrine of God's sovereign choice in mercy is grounded in God's own declaration in Romans 9:15-18, where He articulates His authority to show mercy to whomever He wills. This perspective emphasizes God's electing grace, where He chooses individuals not based on their merit but according to His divine purpose and will. The truth that God can have mercy on whom He chooses highlights His sovereignty and grace, demonstrating that no one can earn God's favor and that His decisions are rooted in His perfect righteousness and wisdom.