Why is the concept of grace significant in prayer?

The concept of grace is pivotal in the life of a believer, especially in prayer. Without grace, we would have no grounds to approach a holy God, as our sins would separate us. David's appeal in Psalm 143 for God's gracious response underscores that it is only through grace—unmerited favor—that we can engage with God. This reflects the broader Reformed understanding that we are entirely dependent on God's grace for justification, sanctification, and the strength to persevere in faith. When we pray, we do so on the basis of Christ's righteousness and God's faithfulness, trusting that He will respond in grace to our petitions.