I'm writing quite a bit at the moment about reactionary or Counter-Enlightenment Catholicism, and I intend to write some more on the same subject. It may be useful to define briefly what I mean by these terms.
The basic principles of Counter-Enlightenment Catholicism were as follows:
1. Catholicism was the true religion, and all other religions were false. Men were required by God to profess the Catholic faith if they were not to be damned (subject to certain exceptions, which could be drawn broadly or narrowly). It could be verified quite easily that Catholicism was true.
2. The Catholic Church had supreme authority in the spiritual sphere, together with certain rights in the temporal sphere. The Church and the State inhabited different spheres, and each possessed authority within its respective domain. A distinction between the two domains existed, and human society was not to be governed as an outright theocracy (except perhaps in the Papal States, where the Church and the State were inseparably fused). However, the spiritual domain was ultimately superior to the temporal domain, and this meant that the Church had an 'indirect power' (potestas indirecta) over State affairs in appropriate cases.
3. The liberal doctrines of freedom of conscience, separation of Church and State, and state neutrality between different religions were to be rejected. These ideas were wrong both in principle, because men were duty bound to profess the true religion, and in practice, because they were inimical to the social order and would result not in human freedom but in the tyranny of the State. They were being spread in part by an international conspiracy of Freemasons, and perhaps Jews as well.
4. Although men could not be forced to become Catholics, the civil authorities could and should intervene to prevent or restrict the promotion and practice of false doctrines and religions. The individual conscience was beyond the reach of civil and ecclesiastical authority. However, conduct tending to undermine the true religion and men's duties towards God was not to be accepted any more than conduct undermining men's loyalty to the State and the civil authorities.
5. Nonetheless, religious pluralism could be tolerated in practice if necessary. This was a pragmatic concession granted in recognition of the fact that it was likely to represent the lesser evil in countries with a majority or a large minority of non-Catholic subjects.
These principles were asserted with particular vigour by popes and theologians in the century that followed the French Revolution of 1789, though in origin they were much older. They remained official Catholic doctrine until the Second Vatican Council (1962-1965). Many Catholics, particularly in the United States, were lukewarm or hostile towards them, however, and the Church as a whole began to adopt a more pragmatic approach to the modern world from the time of the pontificate of Leo XIII (1878-1903).
On the political side of the fence, the last government to accept the Counter-Enlightenment Catholic agenda was that of General Franco in Spain (1939-1975), though the Salazar regime in Portugal (1933-1974) ran it a close second. The Vatican's 1953 Concordat with Franco was the Church's last traditional Concordat. Article 1 provided: "The Catholic, Apostolic and Roman religion will continue to be the sole religion of the Spanish Nation and will enjoy the rights and prerogatives due to it in conformity with divine law and canon law".
The Church and the State
A good example of the orthodox Catholic attitude towards Church-State relations is found in the Expositio Methodica Juris Canonici of Ludovicus Huguenin (1867):
The higher status of the Church does not injure the independence of civil society.... [T]he civil power is independent in its own sphere - that is, in purely temporal matters.... There is no doubt that [the] spiritual power, when it pertains to Christian citizens, includes an indirect power over civil society. Even in purely temporal matters, insofar as they relate to religion, civil society should defer to the Church, because God does not wish that the temporal good of mankind should be promoted with detriment to his spiritual and eternal good.... The indirect power of the Church perfects political society. Indeed, it protects rulers against rebellion and peoples against excesses of the civil power. It limits both rulers and subjects to the sphere of their duties.
When could false religions be tolerated?
This is the answer provided by Felix Cappello in the 6th edition of his Summa Iuris Publici Ecclesiastici, published in 1954:
It is manifestly clear from what we have said above on the duty of the State towards the catholic religion and the Church that the aforementioned liberty or tolerance can never be granted as of right.... But if a majority, or at least a large part, of the people professes a religion other than the catholic religion, the public authorities can, on the grounds of an urgent political necessity or in order to avoid a greater evil, tolerate the false religion as the lesser evil.
Freedom of worship may therefore be allowed to the extent that the following conditions are satisfied:
1. The tolerance is civil, and not religious. The latter includes professed indifference regarding all religions. Consequently, actual approval cannot be given to something which is evil or to a false religion.
2. The greater evil cannot be impeded by any other means.
3. In accordance with its remedial purpose, it is understood that it is pragmatic and temporary, lasting for a period no longer than the time for which serious reasons of public order persist.
4. The tolerance does not impede the prudent teaching of the truth and endeavours to restore a proper legal order.
....Since freedom of worship... viewed in general terms, is excused by necessity and by necessity alone, it is clear that its extent, be it greater or lesser, must be measured on the basis of actual necessity, so that, when the necessity ceases to apply, the aforementioned freedom must be abolished or restricted. If, therefore, a lesser extent of freedom is sufficient - i.e. a more restricted degree of freedom - this alone and nothing more can and should be conceded: justification is lacking in the absence of necessity.
A note on the liturgy
The relationship between the Church and the State was to some extent reflected in the traditional Catholic liturgy. The great English rubricist Fr Adrian Fortescue had this to say in The Ceremonies of the Roman Rite Described:
No civil distinction affects any ceremony in church, except that the Pontifical and Caerimoniale episcoporum grant certain privileges to "princes." This case can hardly occur in England.
Footnote - A "maximus princeps" may have a place in the sanctuary. He is given a book of the gospels to kiss (not the one used) after the gospel. He is incensed after a bishop (but Kings and the Emperor - the Roman Emperor - before); he is given the kiss of peace. "Magistrates, barons, and nobles" receive this after all the clergy.