How do we know God saves through grace and not works?

The doctrine of salvation by grace alone is foundational in Reformed theology. Paul explicitly argues in Romans 9 that it is not up to our desire or effort ('not of him that willeth, nor of him that runneth'), but entirely dependent on God's mercy ('but of God that showeth mercy'). This highlights the sovereign grace of God, indicating that our salvation is not a result of our own works or decisions but rather God's sovereign choice to save whomever He wills. This understanding leads us to rest entirely in Christ for our righteousness rather than our own actions.