How do we know that salvation is by grace and not by our works?

The doctrine of salvation by grace alone is firmly established in Ephesians 2:8-9, which instructs that we are saved through faith, and that not of ourselves; it is the gift of God, not of works, lest any man should boast. This foundational truth asserts that human effort has no role in salvation, thus removing any possibility for boasting. Believers rest in the assurance that their salvation is entirely the result of God's unmerited favor freely given, affirming that it is His work alone that brings us to faith and eternal life.