Prof. Francis Beckwith, an expert in Catholicism, dives into the differences between Catholic and Protestant beliefs on justification, exploring concepts like praying to saints and purgatory. He delves into the historical context of the Reformation, Martin Luther's actions, and the impact on views of purgatory and post-baptismal sin. The discussion also focuses on the interpretation of Abraham's justification by faith in Romans 4 and the multi-faceted concept of justification in Catholicism, involving ongoing actions, obedience, grace, and salvation.