Here are some quotes from RC Sproul's book: Faith Alone: The Evangelical Doctrine of Justification
"Does saving faith require a trust in the righteousness of Christ alone as the grounds of our justification? Or may a person have a different view of the gospel and still be a Christian?"
"It is to Rome's credit, in my opinion, that she placed anathema on what she believed to be a false and heretical gospel. If sola fide is a distortion of the biblical gospel, surely it deserves such anathema. If the Reformers were preaching and teaching a false gospel, then they were apostate and deserved the labels put on them by Vatican I, 'schismatics and heretics.'"
"The Reformation was waged, not over the question of justification by faith, but over the issue of justification by faith alone. It was the sola of sola fide that was the central point of dispute."
"I said that if justification by faith alone is essential for salvation, and if Rome rejects justification by faith alone, then the conclusion follows by resistless logic that Rome rejects an essential truth of Christianity. When I use the word, if, here, I do so for the sake of the present argument. In my mind there is no if about it. I am convinced, as were the Reformers, that justification by faith alone is essential to the gospel, and that Rome clearly rejects it."
"Agreement between Rome and Evangelicals can be reached in several ways. One is for Evangelicals to abandon their historic position of sola fide. A second is for Rome to adopt sola fide as its official doctrine. The third is for agreement to be reached that sola fide is not essential to the gospel."
"To indicate that the Roman view is inadequate, or it falls short, is a gentle criticism. In my estimation, it is too gentle. One could construe this statement to mean that, though it has short comings and is less than adequate, the Roman 'version of the gospel' is still just that, a 'version of the gospel.' The New Testament makes it clear that there is only one gospel. An 'inadequate' gospel is not the gospel. A gospel that 'falls short' of its essence is not a true gospel and must be vigorously rejected."
"I can imagine no Reformed theologian from the 16th century to the present day suggesting that the Roman Catholic view is not a serious threat to the gospel."
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AMEN!