Consider this, (Patrick Toner, "Infallibility", 1910 Catholic Encyclopedia)
It is also generally held, and rightly, that questions of dogmatic fact, in regard to which definite certainty is required for the safe custody and interpretation of revealed truth, may be determined infallibly by the Church. Such questions, for example, would be: whether a certain pope is legitimate, or a certain council ecuмenical, or whether objective heresy or error is taught in a certain book or other published docuмent.
Therefore, any one who makes this decision in purely personal capacity, and not as an organ of ecclesiastic authority, could never give us that definite certainty which is needed in the question. Therefore, we cannot make the decision at all, and should not presume to, only the Church in future, if at all, as in the case of Honorius, can make such a decision.
And as it was then, so it is now. No one had anathematized Honorius in his lifetime, yet it was not said that they had all become heretics or schismatics by doing so. Not even St.Maximus, who defended the Faith when it was doubted by some, and considered the seemingly smallest point of it, worth dying for, as he did.
Gregory I, firstly, when we say God subsists in Three Divine Persons, we mean that the Three Divine Persons are God. Likewise, we are to understand that when the Church of Christ is said to subsist in the Catholic Church, the Catholic Church is said to be the very Church of Christ.
In number 8 of the Dogmatic Constitution Lumen gentium ‘subsistence’ means this perduring, historical continuity and the permanence of all the elements instituted by Christ in the Catholic Church[8], in which the Church of Christ is concretely found on this earth.
Right.
Nevertheless, the word “subsists” can only be attributed to the Catholic Church alone precisely because it refers to the mark of unity that we profess in the symbols of the faith (I believe... in the “one” Church); and this “one” Church subsists in the Catholic Church.
Right.
As for,
It is possible, according to Catholic doctrine, to affirm correctly that the Church of Christ is present and operative in the churches and ecclesial Communities not yet fully in communion with the Catholic Church, on account of the elements of sanctification and truth that are present in them.[9]
The Church may be said to be present where any soul is in good faith. For if the only means of grace, truth and salvation is the Catholic Church, then she must be present to separated individuals in good faith.
And the Council also correctly said,
Whosoever, therefore, knowing that the Catholic Church was made necessary by Christ, would refuse to enter or to remain in it, could not be saved.
The obligation of spreading the faith is imposed on every disciple of Christ, according to his state.
So, again, the traditional Catholic doctrine that good faith cannot simply be presumed and left at that, but rather that the Faith must be preached by us as a holy obligation, is maintained.
I agree with Robert Sungenis on this one. God permitted a Council like this so that those liberals who had already willed, through their own fault, to depart from divine truth might fancy themselves as having found an excuse. As St.Peter says of those who do the same with St.Paul, "they being unstable wrest to their own destruction". Those who interpret it in the light of Tradition are always safe in doing so. We can and ought to do neither more nor less.
The important thing is to know the truth and hold the Faith, and gently instruct others who may stumble or doubt.