How do we know salvation is by grace through faith alone?

The doctrine of salvation by grace through faith alone is central to the gospel message, affirmed in texts such as Ephesians 2:8-9, which states that we are saved by grace through faith, and not of ourselves. This underscores the idea that human works or adherence to the law cannot contribute to our salvation. In Paul's confrontation with Peter, he reiterates this point by emphasizing that adding any works, whether Jewish law or otherwise, to faith in Christ compromises the gospel message. Therefore, true salvation rests entirely on Christ's merits, not on our actions.