Why is grace alone sufficient for salvation?

The doctrine of grace alone teaches that salvation is entirely the work of God's sovereign grace, completely apart from human effort or merit. Ephesians 2:8-9 underscores this principle, highlighting that we are saved by grace through faith as a gift from God, not from our works so that no one may boast. This perspective is crucial as it emphasizes that our standing before God relies solely on the righteousness of Christ, whose perfect sacrifice satisfies God's justice. Any attempt to add human works to grace diminishes its purity and turns grace into a system of merit, which aligns with the belief that we bring nothing to our salvation, being completely dependent on God's mercy.