Yes, in matters of salvation one absolutely must be subject to the Roman Pontiff to be saved. Boniface uses the analogy of the Ark of Noah, outside of which all perished, and the Church being the Ark, outside of which no one can be saved.
Right: and while one cannot be saved outside the Ark, one could be tethered to the Ark, still in the water, but, nevertheless, somewhat safe being tethered to the Ark. This is by exception, of course. The ordinary way and the best way is to simply be on the Ark.
One might suggest that Protestants while not in the Ark, are tethered to the Ark through our Common Baptism?
So then you acknowledge the contradiction between the De fide definition of Boniface VIII of the absolute necessity for the salvation of every human creature to be subject to the Roman Pontiff and the Vatican II religion which states that schismatic and heretic sects, which are not subject to the Roman Pontiff, but reject the Roman Pontiff, are a means of salvation?
1) The Protestant Reformation had not happened yet. Thus, to attempt to use Boniface's statement to answer questions like "What is the relationship of the Protestant sects to the RCC" goes beyond the text. How can we use Boniface's text to answer questions---that were not being asked? How can we use Boniface's text to answer questions Boniface did not have in mind when he authored the text? Boniface had never heard of a Protestant!
See--this is what I mean by context. You rad trads apparently do not care about context. You just see something written in Latin, see it is from a pope before Vatican II, and then assume it teaches rad trad 1950's Catholicism. You then chant with glee and claim victory.
What DID Boniface have in mind when he authored that text? He had in mind and was answering who is the ultimate authority in the Church: the king or the pope? Answer? The pope. We do not look to the king/emperor to define doctrine or otherwise answer questions about matters of salvation. But none of this matters to you. What you WANT Boniface to be saying is "All Non-Catholics are going directly to Hell. Only Catholics go to heaven. That means every Protestant on this site better convert or they will go directly to jail when they die, not pass go, and not collect $200."
2) There is no contradiction between Vatican II and Boniface. Vatican II did not say "The Church has now decided that in matters of salvation, the king/emperor/secular authority is competent to answer theological questions and define doctrine, the pope is a secondary authority and answers to the state." Can you find where Vatican II DID say that? Where did Vatican II revoke papal authority and put the state in charge? I mean--if that happened, I am sure Biden and Pelosi would love to refashion the Church after their leftist image.
You are just mad because Vatican II does not say "We define, assert, and declare infallibility that all non-Catholics are going to Hell. If you want to go to Heaven, you better join the Catholic Church. Otherwise, you are doomed."
3) Is it "Outside the Church no salvation" or "Without the Church no salvation?" "Extra" can be translates "without" especially when speaking in the abstract. This is an argument you have not yet answered, by the way.