How do we know that God's promises are not dependent on man's obedience?

In Romans 3, Paul emphasizes that God's promises are not contingent on human obedience because all have sinned and fall short of the glory of God. If God's promises relied on human effort, they would never be fulfilled due to man's inherent sinfulness. Paul makes it clear, quoting Scripture, that there is none righteous, no, not one. Therefore, God's sovereignty and faithfulness are demonstrated even through human disobedience, ensuring that His divine purpose prevails, independent of man's actions.