Hey, Pneuma. Good to hear from you on this. I think the answer to the question when the discontinuity initially began is that there never was any period of pure orthodoxy unadulterated by confusions and misunderstandings. Even while the apostles walked the Earth, the extant documents are rife with evidence showing errors. The Judaizers were driving Paul up the wall all during this time, of course. Even Peter had a bit of a “relapse” on such issues and needed to be taken to task by Paul. … , there was never any mgaically “pure” Church, free of error, to depart from.
The lesson I draw from this – and it’s just my honest opinion looking at the history – is that the Lord’s guarantees to the Church do not mean that the Church is necessarily all going to be moving along unanimously and in perfect harmony. It would be great if God’s people could all agree on everything, but in this world of sin and limited knowledge as opposed to in the hereafter it’s natural to expect disagreements and mistakes. And if this was the state of affairs when we actually had the apostles themselves here, it certainly is no surprise to me that it’s still the case now.
This also, I think, provides the basis for my answer to your point about perspicuity. I think the small core of foundational and truly critical doctrines underlying Christianity are, in fact, quite perspicuous, as one would expect. But I fully agree with what I assume is your view that there are many hard questions where it’s not at all obvious what the right answer is. That’s fine with me. Like in every other part of life, God has not chosen to spoon-feed us clear and easy answers to every question about the faith (just as He has not chosen to give us clear and easy answers to any other complex and important areas in life, like science or mathematics). I think it’s our job to take the clear and essential doctrines and stand by them firmly, and with respect to the hard questions, use our brains and do our best to come to our best answers, maintaining humility and a sense of perspective. I think that’s sort of what Paul was telling the Romans when he said not to get hung up on debatable questions – he was telling us that we should tolerate each other’s differences of opinions on those debatable questions (not the essentials of the Gospel, where we know Paul was very forceful that only one answer was permissible).
Dear CThomas,
Code:
I can share most of the single sentences here. What I have to say is mainly about the general framework.
Plenty of witnesses to the existence of dissenters in the NT. Agreed. The basic distinction we should draw IMHO is between
presence of dissenters against the legitimate authority of the legitimate leadership, and the going astray of the leadership itself.
I suppose we can agree the NT points to the presence of legitimate authority in the New Covenant. It could be enough a reading of Jude in connection with Numbers 16. The issue is Korah’s rebellion, the rebellion against legitimate religious authority. We get that the New Covenant too has a legitimate religious leadership, the rebellion against which is considered not less grave than Korah’s, and that there were “Korahs” in the I century. If we assume that there always were some Korahs in the centuries from the I to the XXI, we have continuity.
We on the contrary assume a momentous discontinuty, IMHO, if we say that from a given time, there were no more Korahs for the simple reason that a legitimate authority was no more. This is what we must consider by stating that the leadership of the visible Church went astray and astray since … ( when ?).
Here is the when again ! It looks unavoidable.
I’d say in stating such a discontinuity we should accept a really heavy burden of proof, since that amounts to stating that the principle of authority, as witnessed to in the NT, has no more place in the picture of the Church since a given time.
Have I to believe that the guys who would dissent from the leadership, who would attack it and its teachings, at a given moment are no more "“Korahs”, and suddenly have to be seen as the heroes of the day ? Well, for sure not all of them can be heroes, since their attacks would come from different and often opposite perspectives.

Who then were the heroes, and the first ones among them ?
BTW can’t we see a striking continuity between the NT and the Apostolic fathers on the issue of legitimate authority ? Let’s say from Hebrews ( “obey your leaders”), through Clement, to Ignatius ( “obey your bishop”) ? Do you accept episcopacy, as outlined in Ignatius, or do you consider it a deviation ?
On perspicuity: who tells me what is essential ? Is there general agreement on a definition ? (I understand you mind the Church went astray even about the perspicuous core, as you define it, am I correct ? )
Let’s say anyway salvation is an essential issue. I guess more or less people would agree on that. Is soteriology a perspicuous field ? Is there any general agreement about that among those who have it that the (leadership of the visible )Church went astray ? Can it be safe considering that one of the proposed soteriologies is precisely so perspicuous to make the supposed error of the one(s) taught by the Catholic Church manifest ?