How do we know God's grace is essential for salvation?

We understand from Ephesians 2:8-9 that we are saved by grace through faith, and this is not of ourselves; it is the gift of God. This encapsulates the core of Reformed theology, which asserts that salvation is not a result of our works but purely an act of God’s grace. In the sermon, it's emphasized that left to ourselves, we are rebellious and unfaithful, much like the Israelites in Judges, who turned away from God. It is only through God’s grace that anyone can enter His kingdom or possess the ability to respond positively to His call. Thus, recognizing the necessity of grace reminds us of our total dependence on God for salvation.