How do we know that salvation is entirely by grace?

Scripture consistently supports the doctrine of grace in salvation. Passages such as Ephesians 2:8-9 clearly state that it is by grace that we are saved through faith, and this not of ourselves; it is the gift of God. This underscores the principle that human works cannot earn salvation, and rather, it’s solely based on God’s mercy and the redemptive work of Christ. Furthermore, Romans 3:24 teaches that we are justified freely by His grace through the redemption that is in Christ Jesus, solidifying the foundational belief that there is no merit on our part that contributes to our salvation. Therefore, salvation being an act of grace emphasizes God's sovereignty in choosing and saving His people.