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

The doctrine of sovereign grace emphasizes that salvation is entirely the work of God, without any contribution from human effort. Ephesians 2:8-9 clearly states that we are saved by grace through faith, and this is not of ourselves; it is the gift of God. The Passover illustrates this principle: the Israelites did not save themselves; rather, it was God who provided the means of salvation through the blood of the lamb. Our works cannot earn favor with God because all have sinned and fall short of His glory (Romans 3:23). Only through Christ's atoning sacrifice can justice be satisfied, thus demonstrating that salvation is by grace alone.