How do we know that God has done a work of grace in our hearts?

The assurance that God has done a work of grace in our hearts is evidenced by our willingness to receive Jesus Christ. This willingness is not the result of our choice but a confirmation that God's Spirit has transformed our hearts. As Psalm 103:3 notes, God makes His people willing in the day of His power, showing that it is by His initiative, not by our efforts, that we turn to Him in faith. Realizing that we could not come to Christ without the initiative of God provides us the confidence that our faith is genuine.