Rapid moral decay in Western society has in recent years encouraged Roman Catholics and Protestants to work together in order to address social ills such as abortion, homosexuality, and more. Unfortunately, however, many people have thought that such social and moral cooperation requires a downplaying of theological differences between Roman Catholicism and confessional Protestantism. Some have even gone so far as to say that Roman Catholics and Protestants no longer disagree substantively over the matter of justification by faith. Such a viewpoint is naïve. True, Roman Catholics believe in justification by faith, but they do not believe in justification by faith alone. Nearly five hundred years after the Roman Catholic view of justification was formalized at the Council of Trent, the Catechism of the Catholic Church still teaches that justification is a process that begins with the work of baptism, continues through the sacrament of penance, and is finally granted on account of the merit of our good works in addition to our faith. Such a view is fundamentally at odds with the biblical view as summarized in orthodox Protestantism, namely, that our good deeds are in no sense the grounds of our right status before the Father (Rom. 4; Gal. 2:15–16). We maintain that Jesus’ perfect righteousness is the sole basis for our justification (2 Cor. 5:21). To say otherwise is to water down the righteousness of God. When we add our works to our faith as the instrumental means of justification, we deny the sufficiency of Christ and mix our impure deeds with His perfect obedience, effectively polluting the grounds of our righteousness before the Father. If He were to declare us righteous based on this impure basis, He would not be perfect. Even the best of our deeds, question and answer 62 of the Heidelberg Catechism tell us, are tainted with sin. This includes our repentance and the faith associated with our baptism into Christ through faith alone. When we come before God with our righteous deeds, we must confess that they still fall far short of His demands. We must repent even of our righteousness, which is what the prophet Isaiah does in today’s passage. John Calvin comments on Isaiah 64:6 that we must acknowledge that God would be just to punish us even for our “good” deeds.