"But Tim, there are real Christians in the Roman Catholic Church!"
For those who are circumcised do not even keep the Law themselves, but they desire to have you circumcised so that they may boast in your flesh. But may it never be that I would boast, except in the cross of our Lord Jesus Christ, through which the world has been crucified to me, and I to the world. - Galatians 6:13, 14
Ideas have consequences. So does doctrine. That there are true Christians who trust the blood of Jesus Christ alone to make their garments white who worship in the Roman Catholic church is no less extraordinary for being true. They are the exception that proves the rule. They go against the grain of their entire doctrinal system and many Anglicans and Protestants across the centuries put their life at risk to recover Biblical doctrine, calling to those in the Roman bondage to repent and believe. Those who imply that Luther and Calvin and Knox were fools for doing so are ignorant of what Scripture and Rome teach, or they are opposed to the very idea that ideas have consequences and that it is the job of the Church to make disciples of all men, baptizing them in the Name of the Father, Son, and Holy Spirit and teaching them to obey everything He commands.
But really, we do run into the most basic failures of logic in our blind world. Systems of doctrine which are heretical (of which Rome is our primary example, here) are generally held by those who align themselves with the churches who claim that system of doctrine. What a world we live in that we must say such an inane thing!
Which is to say, priests sacrifice Christ over and over again... This is the primary duty of their ordination. They are priests, after all—not pastors—and they preside over the sacrifice of the Mass. This is contrary to the "once and done" teaching of Hebrews (e.g. Hebrews 7:27; 9:12, 28; 10:10).
Does it matter?
Luther and Calvin and Knox thought it does. And you? Or are generalizations so distasteful to you that you will never allow that any system of doctrine can be denounced as heretical, nor that any person who is a member of the communion holding to that system of doctrine can be expected to hold to that heresy and be in spiritual jeopardy because of their membership in that heretical communion?
Ideas have consequences. Doctrine has consequences. Rome has anathematized my faith and doctrine for over half a millenium, now, and they're right to do so if their dogma is what Scripture declares. So I reciprocate and anathematize their system of doctrine (as they have mine) because I know their system of doctrine is a fulsome denial of Romans and Galatians, for starters. But I don't stop there: I go on to the work of warning Roman Catholics to leave the dead to bury their dead, to turn away from the dead and enter Christ's true church where the doctrine of salvation has not been (and is not) corrupted by the systematic monetization of justification-not-by-faith-alone which is the heart of their error and which, tragically, their purported "ecumenical council" of Trent deposited permanently at the center of their church.
Do we really care for souls? Do we really love anyone? Do we really see deceptions and grieve over them, or are we simply committed to the laissez-faire spirituality Rodney King summarized best when he spoke for a decadent age, asking "Can't we all get along?"
The Apostle Paul writes the book of Galatians defending the doctrine of justification by faith alone and we respond, how? "Oh, Paul, there you go again getting on your high horse! Don't you know how many sincere and well-meaning Judaizers there are? And how can you know men's hearts? How harsh you are, Paul, telling them that, while they're at it, you wish they'd just go ahead and cut it all off. Grow up, Paul; are you a misanthrope? Take a chill pill, dude! I mean, really!"
Now you might resent my putting it this way, but in every discussion with weak and sentimental moderns we find that the exception to the rule is all that matters—never the rule.
Roman Catholicism is a heresy and its main heretical dogma is most clearly seen in the Tridentine documents which, according to church law, can never—may never—be repealed. Which is to say the magisterium is stuck down a mine shaft they can never escape without denying one more false doctrine which is the authority of church tradition.
And their false doctrine really does lead most of the souls under the care of those defending and teaching and preaching and practicing that false doctrine to Hell.
If all we ever feel compelled to say is that there are some people who are real Christians in the Roman Catholic Church and some parish priests who don't sodomize little boys, what have we said that anyone needs to hear?
Nothing—nothing at all. Everyone knows it and no one will argue with it.
Which really is why saying it is so very popular.
But what does a true Christian shepherd say to Rome and her subjects?
A true Christian shepherd says to Rome and her shepherds what the Apostle Paul says in Galatians: if you continue to trust your sacraments and good works to save you, there is no hope for you of eternal life.
We need to keep in mind the statement that we moderns are given over to the morbid habit of sacrificing the normal on the altar of the abnormal. Rome is blind masters leading their blind subjects further into their blindness. That is the norm with Rome and unkindness is not saying it, but failing to say it.
The abnormal is Roman priests and parishioners who reject Rome's heresies and truly believe in the work of Christ alone for their salvation; souls who trust in Jesus Christ and, therefore, love God and their neighbor. Faith working through love. But such souls are the exception to the rule and we must not focus on these abnormalities so we may not have to blow the trumpet warning of the normalities of the false doctrine Rome is steeped in to her neck.