How do we know God shows mercy to some but not to others?

The concept of God choosing to show mercy to some and not to others is rooted in the sovereignty of God. Romans 9:15 states, 'For He says to Moses, I will have mercy on whom I will have mercy, and I will have compassion on whom I will have compassion.' This underscores that God's mercy is an act of His divine will, independent of human effort or worthiness. Thus, it is essential to recognize that God's mercy aligns strictly with His sovereign plan, serving to demonstrate His ultimate authority and purpose over creation.