How do we know that justification is by faith and not works?

The doctrine of justification by faith is firmly established in Romans 3, where Paul teaches that 'by the deeds of the law, there shall no flesh be justified in his sight.' This confirms that our standing before God is solely based on Christ's righteousness as it is imputed to us through faith, and not by any works we perform. This is further affirmed in Ephesians 2:8-9, which states that we are saved by grace through faith, not of ourselves; it is the gift of God, not of works, lest any man should boast. Understanding this distinction is vital for grasping the heart of sovereign grace theology.