How do we know grace alone is an essential doctrine?

The doctrine of grace alone is rooted in Scripture, asserting that salvation is entirely by God's grace, without any works on our part. Ephesians 2:8-9 states, 'For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast.' This affirms that human merit cannot contribute to salvation, as it is a work of God alone. Throughout the Bible, we see examples of God's mercy and grace in action, culminating in the sacrificial death of Jesus Christ, which secured redemption for His people.