Heck, some of the things Pius XII said and did make me question his orthodoxy.  I think that the Cardinals should have challenged him on these.  Despite all that, however, I am certain with the certainty of faith that he was a legit pope.  But what do you say to those sedevacantists who claim he was illegitimate also?  Based on what principle is that wrong?  They're only doing the same thing with Pius XII that you do with Paul VI.  They called out some manifest heresy and declare that the See was vacant during the putative reign of AntiPope Pius XII.

I am not sure Religious Liberty per se is "heresy" in the strict sense either.  I think it's grave error, but where's the dogmatic definition that it explicitly rejects?

Quanta Cura: “…against the doctrine of Scripture, of the Church, and of the Holy Fathers, they do not hesitate to assert that ‘the best condition of civil society is that in which no duty is attributed to the civil power of restraining by enacted penalties, offenders against the Catholic religion, except insofar as public peace may require.’
“From which totally false idea of social government they do not fear to foster that erroneous opinion, most fatal to the Catholic Church and the salvation of souls, called by Our Predecessor, Gregory XVI, insanity, viz., that ‘liberty of conscience and worship is the proper right of every man and ought to be legally proclaimed and asserted in every rightly constituted society’.”

Dignitatis Humanae (Vatican II): “This Vatican Council declares that the human person has a right to religious liberty. Such liberty consists in this: that all men must be immune to coercion whether on the part of individuals, social bodies or any human power so that in religious matters no one is constrained to act against his conscience or prevented from acting in accordance with his conscience in private and in public, alone or with others, within due limits [these due limits are defined in paragraph 7 as being those of public peace and morality].

https://romeward.com/articles/239750983/religious-liberty-the-failed-attempts-to-defend-vatican-ii

7. The right to religious freedom is exercised in human society: hence its exercise is subject to certain regulatory norms. In the use of all freedoms the moral principle of personal and social responsibility is to be observed. In the exercise of their rights, individual men and social groups are bound by the moral law to have respect both for the rights of others and for their own duties toward others and for the common welfare of all. Men are to deal with their fellows in justice and civility.

Furthermore, society has the right to defend itself against possible abuses committed on the pretext of freedom of religion. It is the special duty of government to provide this protection. However, government is not to act in an arbitrary fashion or in an unfair spirit of partisanship. Its action is to be controlled by juridical norms which are in conformity with the objective moral order. These norms arise out of the need for the effective safeguard of the rights of all citizens and for the peaceful settlement of conflicts of rights, also out of the need for an adequate care of genuine public peace, which comes about when men live together in good order and in true justice, and finally out of the need for a proper guardianship of public morality.

These matters constitute the basic component of the common welfare: they are what is meant by public order. For the rest, the usages of society are to be the usages of freedom in their full range: that is, the freedom of man is to be respected as far as possible and is not to be curtailed except when and insofar as necessary.

http://www.vatican.va/archive/hist_councils/ii_vatican_council/docuмents/vat-ii_decl_19651207_dignitatis-humanae_en.html

I think this is an extremely important question, i.e. whether religious liberty as taught by the Conciliar Church is heresy.

I hate to bring up John Daly in light of some of the discussions in this thread regarding him, but Mr. Daly puts concisely into juxtaposition the teaching of Pope Pius IX in Quanta Cura with the teaching of Vatican II:


Pius IX says that the view that the civil power may not restrain "offenders against the Catholic religion" is contrary to "the doctrine of Scripture, of the Church, and of the Holy Fathers" - i.e., it is against Revelation. Thus, Vatican II seems to express an opinion against Revelation, which would be an anti-gospel and heretical.

Now, you might want to make a distinction in that Vat II mentions "morality" as well as "public peace" as justifying action by the civil power to restrain liberty, but the discussion of "morality" by the Vat II council does not I believe allow a meaningful distinction on that ground, since said "morality" has nothing to do with "offenses against the Catholic religion." Here's paragraph 7 of DH:

I don't want to derail the thread but I'd like to hear your thoughts on this, Ladislaus - or anyone.

DR