How do we know God's grace is free and not based on our works?

God's grace is fundamentally characterized as unearned and undeserved favor towards sinners. As Paul writes in Ephesians 2:8-9, we are saved by grace through faith, and this not of ourselves; it is the gift of God, not of works, lest anyone should boast. This illustrates that salvation is a work of God alone, not dependent on human efforts or decisions. Anything that ties salvation to our actions would nullify this grace, making it a matter of personal achievement rather than divine mercy. The distinction between works-based salvation and grace is central to the doctrine of sovereign grace, highlighting that only through God's initiative are we brought into a right relationship with Him.