I disagree that Vatican II taught novelties. I think they are developments; rather striking, but still developments. They were certainly not more radical developments than the Jerusalem Council suddenly making circumcision optional for Gentile converts, or even Vatican I proclaiming papal infallibility as a de fide dogma in 1870.
I just put up a post today which is a defense of the Assisi ecumenical gatherings by a priest, utilizing St. Thomas Aquinas at length.
As Fr. William G. Most has documented, there have been “strict” and more lenient traditions of “salvation outside the Church” means throughout history (which ties directly into ecumenism). See his brilliant article: “Is There Salvation Outside the Church”.
I also delve into these matters in great depth in my 2003 article, “Salvation Outside the Church?: Alleged Catholic Magisterial Contradictions & St. Thomas Aquinas’ Views”. It was originally a vigorous debate with an Anglican. I heard that he later became a Catholic.
The “prevailing” Catholic views on religious liberty and tolerance have also differed at different times. The early Church didn’t persecute (punish bodily) for heresy. Then the medieval Church did, and later the view was again towards tolerance: so much so that now the Church strongly urges against capital punishment even for murder.
Thus, the matters of religious liberty and ecumenism (i.e., favoring both) are not at all lacking historical pedigree.
Another example of Vatican II “distinctives” being present before the 1960s is the term, “separated brethren”, which was in use all the way back to Pope Leo XIII. See my post: “‘Separated Brethren’ Term Before Vatican II (1962-1965)”.
I submit that these issues are not nearly as clear-cut as most opponents of Vatican II claim. They are far more complex than they realize.
Radical Catholic reactionaries in particular make these wrongheaded arguments, in their rush to judgment against Vatican II. At first glance they may seem impressive, but once closely scrutinized, they melt away like a snowball on a hot summer day.