CathInfo.com

Cardinal Cushing quoted by his own (favorable) biographer:  "No salvation outside the Church?  Nonsense.  Nobody's [not even the Church?] is going to tell me that Christ came to die for any select group."

Cushing:
CUSHING PRAISES GRAHAM CRUSADE; Cardinal Urges Catholics to Hear the Evangelist
https://www.nytimes.com/1964/10/08/archives/cushing-praises-graham-crusade-cardinal-urges-catholics-to-hear-the.html

Cushing praising Religious Liberty at Vatican II:
https://vaticaniiat50.wordpress.com/2014/09/24/text-of-cardinal-cushings-address-on-religious-liberty/

Cushing at a Methodist Church (well before JP2), trailblazer for Ecuмenism:
[see the black and white picture] https://www.bostonglobe.com/metro/2014/01/13/cardinal-malley-joins-service-sudbury-methodist-church/aWehNqZMfzGahpdCD0DReN/story.html

Cushing's sister was married to a Jew.  Jews had him in their back pocket.  Here he is (per Wikipedia) at Vatican II:

"At the Second Vatican Council (1962–1965) Cushing played a vital role in drafting Nostra aetate, the docuмent that officially absolved the Jews of deicide charge. His emotional comments during debates over the drafts were echoed in the final version:

We must cast the Declaration on the Jews in a much more positive form, one not so timid, but much more loving ... For the sake of our common heritage we, the children of Abraham according to the spirit, must foster a special reverence and love for the children of Abraham according to the flesh. As children of Adam, they are our kin, as children of Abraham they are Christ's blood relatives."

Well, Bishop Williamson would disagree; he traces the rot back to the Renaissance.

It depends on what the agreement/disagreement is about.

I agree that the rot traces all the way back to the Fall of Man in the Garden of Eden. The peak of Christendom was St. Thomas Aquinas in the 1200's. It was all downhill after that.

However, if I woke up tomorrow and found myself in 1961 on a Sunday, and I chose NOT to attend my local parish (or any other parish) for Mass, I would be committing a MORTAL SIN worthy of sending me to Hell for eternity if I didn't repent and confess my sin to a priest before death.

That is what I mean by "The Church was OK before Vatican II".

Heck, the Protestants think the rot goes back before the Council of Trent, and they jumped ship (the ship being the Catholic Church) back in the early 1500's. Were they just forward thinking avant-garde, or were they a bunch of heretics?

Right, of course we could and would be bound to attend Mass in, say, 1961 and that the OFFICIAL teaching and liturgy of the Church were untainted.  So I get what you mean.