Dr. R.C. Sproul writes in his book Faith Alone: “For Rome the declaration of justice [justification] follows the making inwardly just of the regenerate sinner. For the Reformation, the declaration of justice follows the imputation of Christ’s righteousness to the regenerated sinner.” When it comes to justification, the difference between Reformation theology and Roman Catholic theology is not over the necessity of grace, faith, and the obedience of Christ. Rome has always taught that no one can be justified apart from these things. The difference between Rome and the Reformation is that in Roman Catholicism, justification is based on an inherent righteousness, a righteousness that God infuses into us and with which we cooperate in order to increase our justification. For biblical, Reformation theology, justification is based only on the righteousness of Christ, which is an alien righteousness, a righteousness that is not inherently ours because it consists only of Jesus’ good works.
So, the real dividing line between Roman Catholicism and the Reformation is one word—alone. Justification is not only by faith; it is by faith alone. Justification is not only by grace; it is by grace alone. Justification is not only by the work of Christ; it is by the work of Christ alone. If we add even one work of ours as part of the basis for justification, we have missed the gospel. Paul stresses that we are not justified by our works, and he illustrates it by showing that Abraham was justified before he obeyed the law. He was justified by faith alone apart from circumcision (Rom. 4:9–12). The only way to preserve that teaching is to insist that the only meritorious basis for our justification is the obedience of Christ imputed to us. Once we make our justification dependent on an inherent righteousness that combines Christ’s merit and our merit, we have lost the gospel of grace.
The teaching that none of our good works are part of the basis for justification is so clear that many have tried to get around it by saying that since Paul mentions circumcision in Romans 4, he means only that works of the ceremonial law cannot justify us but obedience to the moral law can. This fails to understand that Paul is using circumcision in this text as a preeminent example of the law’s commandments that represents the entire law. John Calvin comments that under circumcision “is included every work of the law; that is, every work to which reward can be due.” Indeed, justification is not by any works wrought by us in righteousness (Titus 3:4–7).