This sermon presents a robust theological critique of key Roman Catholic doctrines—particularly the Mass, penance, and purgatory—arguing that they fundamentally distort the biblical gospel by undermining the sufficiency, finality, and exclusivity of Christ's once-for-all sacrifice. Centered on 1 Corinthians 11 and Hebrews 10, it affirms that the Lord's Supper is a memorial of Christ's completed work, not a repeated sacrifice, and contrasts this with the Catholic Mass, which the sermon condemns as a blasphemous repetition of Christ's atonement. It further exposes penance and purgatory as unbiblical systems that burden consciences, destroy assurance of salvation, and replace Christ's finished work with human effort and priestly mediation. The sermon insists that these doctrines, though presented as spiritual, are spiritually destructive and incompatible with Scripture, calling for continued separation, discernment, and evangelistic urgency toward Roman Catholics, not ecumenical compromise, because true peace and assurance come only through faith in Christ alone.