“The Church recognizes that in many ways she is linked with those who, being baptized, are honored with the name of Christian, though they do not profess the faith in its entirety or do not preserve unity of communion with the successor of Peter.”
— Lumen Gentium §14
A defective profession of faith, no fellowship with the Roman See, and a denial of at least five Sacraments, to boot. Are such things really the grounds for saying that non-Catholics are somehow “within” or “part of” the Church? I saw this quotation today and it sent my head spinning. Refusal of communion with the Holy See, rejection of the Faith on numerous points, and a negation of virtually the entire sacramental order of grace–that is supposed to speak well of Christian unity? If the bar is that low to be “linked with” the Church “in many ways,” then, really, what does it take to be a heretic/schismatic?
Of course, maybe the reality is not so dizzyingly Heisenbergian, after all. To wit:
“22. Actually only those are to be included as members of the Church who have been baptized and profess the true faith, and who have not been so unfortunate as to separate themselves from the unity of the Body, or been excluded by legitimate authority for grave faults committed. “For in one spirit” says the Apostle, “were we all baptized into one Body, whether Jews or Gentiles, whether bond or free.” As therefore in the true Christian community there is only one Body, one Spirit, one Lord, and one Baptism, so there can be only one faith. And therefore, if a man refuse to hear the Church, let him be considered – so the Lord commands – as a heathen and a publican.  It follows that those who are divided in faith or government cannot be living in the unity of such a Body, nor can they be living the life of its one Divine Spirit.“
— Pius XII, Mystici Corporis Christi (1943)
The problem seems to be that whereas Pius XII used the word “reapse” (really, effectively, actually), Unitatis redintegratio §3 used the term “non plene” instead. This is, arguably, not a small difference, since an unreal inclusion automatically entails an imperfect communion, whereas the latter does not entail any real inclusion. If I am not really a member of, say, a teacher’s union, how can I be said to enjoy “imperfect communion” with that union?
Fortunately, it only took twenty years to bleach out such dogmatic madness.
Still, though, some of those gnarly old pre-conciliar popes sounded pretty astute:
“The Church … has done nothing with greater zeal and endeavour than she has displayed in guarding the integrity of the faith. Hence she regarded as rebels and expelled from the ranks of her children all who held beliefs on any point of doctrine different from her own. … ‘There can be nothing more dangerous than those heretics who admit nearly the whole cycle of doctrine, and yet by one word, as with a drop of poison, infect the real and simple faith taught by our Lord and handed down by Apostolic tradition’ (Auctor Tract. de Fide Orthodoxa contra Arianos).
“The practice of the Church has always been the same, as is shown by the unanimous teaching of the Fathers, who were wont to hold as outside Catholic communion, and alien to the Church, whoever would recede in the least degree from any point of doctrine proposed by her authoritative Magisterium. …
“Wherefore, from the very earliest times the fathers and doctors of the Church have been accustomed to follow and, with one accord to defend this rule. Origen writes: ‘As often as the heretics allege the possession of the canonical scriptures, to which all Christians give unanimous assent, they seem to say: “Behold the word of truth is in the houses.” But we should believe them not and abandon not the primary and ecclesiastical tradition. We should believe not otherwise than has been handed down by the tradition of the Church of God’ (Vetus Interpretatio Commentariorum in Matt. n. 46).”
— Pope Leo XIII, Satis cognitum (1896), which, perhaps not so curiously, never cited in the Vatican II documents (though I may be wrong about that)
The irony is even more acute considering what is written in the preceding paragraph:
“He is not saved, however, who, though part of the body of the Church, does not persevere in charity. He remains indeed in the bosom of the Church, but, as it were, only in a ‘bodily’ manner and not ‘in his heart.'”
That stringent warning does not somehow apply to non-Catholics, even as they are described in §15?