How do we know sinners are saved?

The salvation of sinners is grounded in the atoning work of Jesus Christ, who came to save His people from their sins. According to Romans 5:8, 'But God commendeth his love toward us, in that, while we were yet sinners, Christ died for us.' This indicates that salvation is a work of grace, where Christ paid the penalty for sin on behalf of those who could not save themselves. Furthermore, Psalm 130 illustrates that those who cry out for mercy, like David, are met with forgiveness. They are justified—not by their own works, but by faith in Christ's completed work on the cross. The assurance of salvation is based on God's promise to be merciful to whom He will be merciful.