His 1977 extended essay The Church and Unity takes the position that the Church is a visible and historical entity, which from gospel times has been regarded as a single unity. The essay is in large part a response to the Anglican scholar S L Greenslade, whom he places among "objectors" who ask, "Is it not totally unreasonable to pretend that the Church is undivided, when most manifestly it is not?" (p 3).
Butler's argument is that from the Church Fathers until Vatican II, the Church has recognized that "real sacraments, , , can exist outside its boundaries. At the same time, it maintains that these sacraments . . . are among a group of "elements or endowments" which together "build up and give life to" the Church herself" ((p 147).
One must surely agree with Greenslade that sacraments, and the other things that he enumerates, are 'things of the Church'. They are of course at a deeper level, one that Greenslade and I would both wish to emphasize, 'things of God'. But they are things of God given in and to and through the Church. He is also correct, I think, in holding that they are constitutive of the Church. The Church is not something that happens to be responsible for the sacraments; the Church is the Church because the sacraments — and the other holy things — make it such. I think we can go further with many modern theologians and say that the Church is sacramental through and through; and even that she herself is (after Christ, the 'sacrament of God') the sacrament of Christ.It seems to me that Butler is arguing against a "branches of a tree" view of the Church that's frequently found among Anglicans, who will often say that Anglicans are just another respectable branch of Christianity equivalent to Orthodoxy or even Lutheranism. Butler is saying that the Church recognizes some elements of schismatic bodies outside itself, but they are worthwhile primarily insofar as they lead the faithful to the true Church.Since sacraments are constitutive of the Church there is good reason to say that where valid sacraments are given and received there is `churchness' — Greenslade's word, and a very useful one. This, incidentally, is the teaching of the Second Vatican Council, though it uses its own language to express it and nowhere, I think, avails itself of the word `churchness'. (p 146)
But what strikes me is the view among the amateur apologists for Anglicanorum coetibus that there is some special value to Anglican "churchness", as in the commonly cited "precious spiritual treasures of the Anglican patrimony". The use of the term "Anglican" would refer to the dominant form of Protestant Christianity found in England and the British Empire, not pre-Reformation English Catholicism, and this implies that those who come into the Church via Anglicanorum coetibus are in a special class of some sort -- clearly entitled to schismatic artifacts eo be preserved in their own liturgy, their own parishes, and their own bishop.
I don't see this in the writing of prior generations of Anglican converts like Butler, Knox, or Newman. And looking most recently at the suburban Baltimore ordinariate communities, what I'm seeing is that small groups of converts seem to have gotten the idea that if a separate specifically Anglican "cburchness" is a good thing to bring into the Church, then a charismatic or pentecostal "churchness" can tailgate in under the same dispensation. Thus Fr Worgul can dwell on his Baptist formation, and Houston seems to rely on a legalistic interpretation that if a candidate for ordination has been arguably "Anglican" for a minimal period, he's eligible, notwithstanding decades as some other flavor of Protestant.
Under Anglicanorum coetibus, the Church in fact seems to validate the idea that some schismatics can retain a sense of separateness from the Church and cling to what is in fact an incomplete "churchness". What I find in a diocesan parish with conscientious clergy is that we're constantly being challenged to understand the teachings of Vatican II, and indeed to recognize the authority of the Holy Father and our bishop. Yet as a practical matter, it's not hard to find instances where ordinariate parishioners are being told it's OK to wink at both, if not to reject them.
As Butler points out, "churchness" is there, but it's not enough, and it shouldn't be made a fetish.