The Catholic Church has always taught that it is Jesus Christ’s one and only true Church, so that even if the mass of believers leave it, as will happen at the end of the world (cf. Lk.XVIII, 8), still it will not have lost its unity. Thus St Cyprian said that the unity of the Church arises from a divine foundation knit together by heavenly sacraments, and it “cannot be torn asunder by the force of contrary wills.” Souls may fall away or tear themselves away, but the Church they leave behind remains one. On this view “Church unity” can only mean souls coming back one by one into the one true Church.
That is not Vatican II’s view of the Church. By saying (Lumen Gentium #8) that Christ’s Church “subsists in” the Catholic Church, the Council opened the door wide to distinguishing between the two, and to pretending that Christ’s “true” Church is broader than the “narrow” Catholic Church. On this view there are pieces of Christ’s true Church scattered outside the Catholic Church, whereupon “Church unity” means putting these pieces together again without individuals having to convert one by one. This was certainly the view of the brilliant young Council theologian, Fr. Joseph Ratzinger, as is shown by astonishing words of his from soon after the Council, quoted with references in Dr. Schüler’s Benedict XVI and the Church’s View of Itself, pp. 17–19. A brief summary highlights their drift:—
Wherever there is Bishop, Table and Word of God, there is “church.” This true broad Christian communion has been gravely narrowed down over the centuries by Roman centralization, which drove the Protestants to break with Rome. The doctrinal differences should have been lived with. So return-to-the-fold ecumenism needs to be replaced with co-existence ecumenism. Churches must replace Church. Catholics must open up. Conversion will be only for the individual who wishes. Protestant errors are, virtually, Protestants’ rights.
But where is the Faith in all this talk of Church and churches? Or doctrine? Apparently nowhere. And what kind of unity can exist between souls that have beliefs as contradictory as those of Catholics (old-fashioned) and Protestants? It can only be a quite different unity from that of the pre-conciliar Church, and therefore quite a different Church. Indeed young Fr. Ratzinger was working towards the Newchurch. However, the Newchurch’s unity became a problem. Firstly, the unity of the Church is a dogma. And secondly, as Cardinal and Pope, Joseph Ratzinger found himself having to defend Newchurch unity against even wilder Revolutionaries than himself (e.g. Fr. Leonard Boff), for whom the Newchurch “subsists” all over the place, in many different pieces.
So Schüler quotes the Cardinal arguing that the Church of Christ has its complete realization in the Catholic Church, but not so as to exclude its incomplete realization elsewhere (but then how is it one?). Similarly the identity of the Church of Christ with the Catholic Church is substantial but not exclusive (but how can identity be anything other than exclusive?) Again, the complete being of Christ’s Church is in the Catholic Church, but it also has incomplete being elsewhere (but how can a being be complete if part of it is elsewhere?). And so on.
In brief, Benedict XVI’s Newchurch includes elements both Catholic and non-Catholic. But even partly non-Catholic is not Catholic as a whole. Therefore Benedict’s ecumenical Newchurch is, as such, not the Catholic Church.