How do we know that justification is by faith alone?

In Romans 5:1, it states, 'Therefore, having been justified by faith, we have peace with God through our Lord Jesus Christ.' This verse emphasizes that faith is the sole instrument through which believers receive justification. Additionally, the Reformation doctrine of ‘sola fide’ inherently posits that all acts of human righteousness fall short of God’s glory, affirming that no one is justified by the works of the law (Galatians 2:16). The significance of faith alone in justification is not merely academic; it is the crucial assurance for believers who recognize that their righteousness before God rests not upon their own performance but solely upon the merits of Christ, who fulfills God's law perfectly on their behalf.