In charity I feel my obligation to point out a few things.
Lumen Gentium must be understood in light of all the teachings before it. Have you read and researched the many quotes from the Magisterium on this issue?
Here’s a link that will help if you haven’t checked it out already.
To say that the Church never understood NSOC in a literal sense is to say that the Church does not mean what it says. Here are a few quotes to consider, and please realize that they must be understood in the same sense as they have always been understood. If you can find parts from the context of the same document or by the same pope that explains it in the way you think you understand it, please do point that out; otherwise, you cannot reduce these teachings to a meaningless formula:
Infallible: IV Lateran Council 1215: “One indeed is the universal Church of the Faithful, outside of which
no one at all is saved.” Pope Innocent III ex Cathedra.
fordham.edu/halsall/basis/lateran4.html
The Council of Florence (A.D. 1438-1445) From
Cantate Domino — Papal Bull of Pope Eugene IV: (Infallible General Council & Ex Cathedra papal declaration)
The sacrosanct Roman Church…firmly believes, professes, and proclaims that those not living within the Catholic Church, not only pagans, but also Jews and heretics and schismatics
cannot become participants in eternal life, but will depart “into everlasting fire which was prepared for the devil and his angels” [Matt. 25:41], unless before the end of life the same have been added to the flock; and that the unity of the ecclesiastical body is so strong that only to those remaining in it are the sacraments of the Church of benefit for salvation, and do fastings, almsgiving, and other functions of piety and exercises of Christian service produce eternal reward, and that
no one, whatever almsgiving he has practiced, even if he has shed blood for the name of Christ, can be saved, unless he has remained
in the bosom and unity of the Catholic Church.
Vatican I. Infallible Ecumenical Council:
… This true catholic faith,
outside of which
none can be saved …
piar.hu/councils/ecum20.htm
From Pope Leo XII’s encyclical
Ubi Primum 1823-1829:
14. It is impossible for the most true God…to approve all sects who profess false teachings which are often inconsistent with one another and contradictory, and to confer eternal rewards on their members. … By it we are taught, and by divine faith we hold one Lord, one faith, one baptism, and that no other name under heaven is given to men except the name of Jesus Christ of Nazareth in which we must be saved.
This is why we profess that there is
no salvation outside the Church.
[21] He who hears you, hears me; and he who despises you, despises me; and the Church is the pillar and firmament of truth, as the apostle Paul teaches.[22] In reference to these words St. Augustine says: “Whoever is without the Church will not be reckoned among the sons, and whoever does not want to have the Church as mother will not have God as father.”[23]
Encyclical of Pope Gregory XVI,
Summo Iugiter Studio, May 27, 1832:
We shall praise St. Gregory the Great who expressly testifies that this indeed is the teaching of the Catholic Church. He says: “The holy universal Church teaches that it is not possible to worship God truly except in her and asserts that
all who are outside of her will not be saved.” Official acts of the Church proclaim* the same* dogma.
Pope Pius XII,
Humani Generis, Encyclical Letter Concerning Some False Opinions Which Threaten to Undermine the Foundations of Catholic Doctrine, August 12, 1950:
“Some reduce to a meaningless formula the necessity of belonging to the True Church in order to gain eternal salvation. … These and like
errors, it is clear, have crept in among certain of Our sons who are deceived by imprudent zeal for souls or by false science. To them We are compelled with grief to repeat once again truths already well known, and to point out with solicitude clear errors and dangers of error.”
You cannot reduce the teaching of NSOC to a meaningless formula. It means what it says and says what it means. The only question would be how those who are not visibly a part of the Catholic Church can be united to her and joined to her through desire. The answer, as I’ve already pointed out, is that the Church teaches that a desire for baptism (whether explicit as in catechumens or implicit in other cases) suffices to place one IN the Church (as long as it is united with perfect charity). But to say that NSOC does not mean what it says or that it is not a literal teaching of the Church does serious damage to the above solemn Magisterial teachings as well as the abundance of other ones from which I have included on the blog site above. The Church’s teaching is quite clear that only Catholics can enter heaven. The only debated question is how one becomes Catholic and is placed into the Church by desire.