How do we know grace is necessary for salvation?

The necessity of grace for salvation is rooted in the understanding that all humanity is inherently sinful and unable to achieve righteousness on their own. The Pharisee in Luke 18 exemplifies this delusion of self-sufficiency, believing his actions make him acceptable to God. In contrast, the Publican acknowledges his sinfulness and pleads for mercy, demonstrating true repentance and understanding of his need for grace. 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 emphasizes that salvation is entirely by grace, as human efforts fall short of God’s standard of holiness.