While I cannot prove my thesis, I have believed it to be true for many years. I am convinced that the horrendous toll that World War II took upon humanity and especially in Europe, plus the unreal horrors of the Holocaust and it's huge impact upon the Jewish people, was a major spark that helped to cause the Catholic Church to open the doors of salvation to non-Catholics. The 2nd Vatican Council taught for the first time in a definitive manner, that non-Catholic Christians and non-Christians, have the possibility of attaining salvation, via the doctrine of "invincible ignorance". I suppose that World War I and the worldwide depression could have been additional causes, but I think World War II carries the most weight.
What think ye? Could there be something to my thesis or am I completely off base as to why the Catholic Church changed it's interpretation of the age-old salvation doctrine known as "Outside the Church, There is no Salvation"?
The V2 contradictory "clarification" was not directly related to the real horrors WW2 but the defeat of dictatorial powers is related and the arise of a freedom in the West. Thus this is also related to Rome's slow loss of her
unholy unscriptural sword of men to compel conformity amidst the corespondent increasing degree and scope of freedom of speech, which was a substitute for the spiritual power of the NT church. That loss, and the gain of freedom, and finally, her acquiescence of Rome to the spiritual declension of the West as it increasingly rejected obedience to the authority of unchanging Scripture, led to the V2
contradiction/clarification of what had been quote formally clearly declared as regards EENS, as well as other
conflictive interpretations . Although as usual, it was already in contradiction to what the NT of Scripture believed, as well as lacking true unanimous consent of the (so-called) fathers.
Back in the "good ol days" that so many conservative ("true") Catholics seem to yearn for, obedience to the pope included requiring RC rulers to exterminate all she pointed out to be heretics, or they would lose their authority. (Canons of the Ecumenical Fourth Lateran Council, canon 3, 1215)
With that power it was easy then for a pope to thunder,
We declare, say, define, and pronounce [ex cathedra] that it is absolutely necessary for the salvation of every human creature to be subject to the Roman Pontiff.”
"If, therefore, the Greeks or others say that they are not committed to Peter and to his successors, they necessarily say that they are not of the sheep of Christ, since the Lord says that there is only one fold and one shepherd (Jn.10:16). Whoever, therefore, resists this authority, resists the command of God Himself." — Pope Boniface VIII, Unam Sanctam (Promulgated November 18, 1302)
"The sacrosanct Roman Church...firmly believes, professes, and proclaims that..not only pagans, but also Jews and heretics and schismatics cannot become participants in eternal life but will depart into everlasting fire...unless before the end of life the same have been added to the flock; 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.” (Pope Eugene IV and the Council of Florence, Seventeenth Ecumenical Council, Cantate Domino, Bull promulgated on February 4, 1441)
Gradually the scope and degree of Rome's power of "coercive jurisdiction" as the old Catholic encyclopedia (Jurisdiction) put it decreased, although she still had some, and parroted past popes in publshing,
“There is only one true, holy, Catholic Church, which is the Apostolic Roman Church. There is only one See founded on Peter by the word of the Lord, outside of which we cannot find either true faith or eternal salvation. He who does not have the Church for a mother cannot have God for a father, and whoever abandons the See of Peter on which the Church is established trusts falsely that he is in the Church. (Pope Pius IX (1846–1878), Encyclical Singulari Quidem, March 17, 1856)
Moreover even after the loss of practical temporal power of the popes (by 1870, outside Vatican City) yer Rome still had devout followers in an era of overall far greater commitment than what would come, and still bombastically asserted,
"Furthermore, in this one Church of Christ no man can be or remain who does not accept, recognize and obey the authority and supremacy of Peter and his legitimate successors. Did not the ancestors of those who are now entangled in the errors of Photius [the eastern “Orthodox “schismatics] and the reformers, obey the Bishop of Rome, the chief shepherd of souls?...Let none delude himself with obstinate wrangling. For life and salvation are here concerned...” (Pope Pius XI, Mortalium Animos: The Promotion of True Religious Unity), 11, Encyclical promulgated on January 6, 1928, #11)
However, not only had the loss practical temporal power of the popes enabled more opposition, but the defeat of dictatorial powers in WW1 and then especially WW2 by the West (even if with help from the Soviets) sent a message in the West that claims to dictatorial authority in its realm were dangerous and tenuous, with the powerful country of free America itself being an example of just dissent from such.
But as America and the West followed the example of Israel of God in increasingly casting off the laws of God after victories and blessing, resulting in aversion to both absolute moral and doctrinal beliefs, then having no real power to enforce either and becoming somewhat infected with the same declension, a majority of the chef shepherds of Rome acquiesced to the society it found itself in by making itself more palatable to society.
As society increasingly became intolerant of doctrinal absolutes, and thus while Catholic accommodation (Vatican 2+) was not by explicit rejection of EENS, yet by way of "interpretation," rather than Protestants being labelled as "heretics" who needed to actually be in the "bosom of The Church or otherwise often separated at the sword of men, they were affirmed as being separated brethren in whom the Holy Spirit dwelt and and thru whom He worked.
As society increasingly became intolerant of moral absolutes, and while Catholic accommodation was not by official rejection of moral doctrine, yet it allowed broader interpretation of such (thus the number of annulments in the West took off), and more acceptance of aberrations.
As society increasingly became intolerant of political rule, so Rome forsook her past rejection of freedom of religious belief and embraced it.
And while the modernist accommodation of Vatican 2 was very limited, yet it was not the end, and which gave birth to the current and most liberal politically correct pope of Rome, resulting in more divisions among RCs.
Note however, that accommodation itself is not new, for the church of Rome arose as a distinct mode by increasingly taking upon the governmental form and means of the Roman empire in which it found itself.
Nor is declension in conformity to societal pressure unique to Rome (the modern evangelical moment arose to combat doctrinal and moral revisionism, yet it now is increasingly manifesting its own declension), and the battle of the kingdom of God has always been to be in the world but not of the world.
Moreover, accommodation to societal pressure can sometimes be a correction (as in the case of rejection of theocracies and for freedom of religious belief by civil powers). And thus the real problem is that some of modern accommodation is not wrong for RC distinctive Catholic teachings are
not manifest in the only wholly inspired substantive authoritative record of what the NT church believed (which is Scripture, especially Acts thru Revelation. which best shows the NT church understood the OT and gospels).