The document discusses Martin Luther's doctrine of sola fide or "justification by faith alone". It describes Luther's realization that righteousness is not earned by works but is imputed by God through faith in Christ alone. It explains the key aspects of faith for Luther including notitia, assensus and fiducia. The document also contrasts Luther's view of alien righteousness through Christ with the Catholic view of infused righteousness and discusses how faith relates to other aspects of the Christian life like regeneration, sanctification and perseverance.