Why is God's grace necessary for salvation?

God's grace is absolutely essential for salvation, as indicated by Romans 9:16, which states that it is not by human will or effort, but by God's mercy. This biblical truth reflects the Reformed understanding that, due to our sinful nature, we are inherently unwilling to seek God or desire salvation without the transformative work of the Holy Spirit. The preaching of Christ and the gospel serves to reveal this need for grace, encouraging reliance on God's goodness rather than our own endeavors, ultimately leading to true repentance and faith that is granted by God's sovereign will.