How do we know that justification comes through faith alone?

The doctrine of justification by faith alone is rooted in the recognition that we, like the publican, have no righteousness of our own to present before God. In the parable of the Pharisee and the publican, Jesus highlights that only the publican, who cries out for mercy, goes home justified (Luke 18:14). This underscores that it is not our works that justify us, but our faith in Christ alone. Roman 3:28 affirms that a person is justified by faith apart from the works of the law. Thus, genuine faith leads us to acknowledge our sinfulness and rely solely on the righteousness of Christ, who fulfills the law on our behalf.