This is the exact opposite of H.H. Leo XIII in Immortale Dei:
*No it isn't. Pope Leo does not say a State must declare Jesus is Lord.
FWIW I readily admit you and others who personally favor Monarchy are widely and deeply read in the matter; far more than I will ever be.
My only point is I don't recall ever reading HM Church mandating any particular form of government; just the opposite.
Still, I think rehearsing all these arguements are helpful and informative and when it comes to ideas about establishing a Monarchy in America and,as an Irishman, I admire any and all forms of such fruitless causes :)
"*No it isn't. Pope Leo does not say a State must declare Jesus is Lord."
How could you possibly read the two paragraphs of Immortale Dei that I posted and come to this conclusion??
"As a consequence, the State, constituted as it is, is clearly bound to act up to the manifold and weighty duties linking it to God, by the public profession of religion."
The state must profess religion.
"Since, then, no one is allowed to be remiss in the service due to God, and since the chief duty of all men is to cling to religion in both its teaching and practice-not such religion as they may have a preference for, but the religion which God enjoins, and which certain and most clear marks show to be the only one true religion -- it is a public crime to act as though there were no God."
So not just any religion, but the true religion.
So what religion is true? (if you can't answer that question then go back to your Catechism)
"From all these it is evident that the only true religion is the one established by Jesus Christ Himself, and which He committed to His Church to protect and to propagate."
It is true. My thesis is that the feudal system is the most organic to the Divine Law and therefore to the Catholic Church social system, while a democratic state can be compatible with Catholicism, and the American Republic in its ideal form is compatible. The latter, compatibility, is what various popes taught, and you quote some of them. But "compatible" only means that the Church can do her work in America and in the USSR or communist Poland, for example, she (or the sister Orthodox Church) could not. It does not mean that the real conditions -- as opposed to the ideal frozen in time form -- cannot deteriorate to the point when the compatibility vanishes. Or vice-versa, an atheist communist state may remove enough obstacles to the Church and become relatively compatible.
There are ominous signs that the real democratic system is turning from welcoming or neutral to hostile toward religion, both in Europe and in the United States. The legal notion that religion cannot exist in any public space has prevailed. Various freedom of conscience protections as regards abortion or homosexuality are rapidly disappearing, even as the innovations such as gay "marriage" and abortion pill make these protections even more necessary. The Catholic duty of a justice of the peace asked to certify a gay "marriage" is to refuse to do so and to refuse to resign over it; likewise with doctors, nurses and pharmacists who may be mandated to serve the abortion and contraception industry. Is there any doubt that the state will respond with hostility to conscientious objectors as soon as the transitional period of legal fog that we currently have over these issues clears? The compatibility will end when it happens.
Of course, establishing monarchy through, say, a constitutional amendment is a fruitless cause. It will only establish itself following a major crisis and collapse of authority. Or a new feudalism will emerge from the system of private enterprise after the state fails. Moreover, re-establishment of hereditary nobility should probably precede the establishment of monarchy. But I do not call for establishment of either. I urge the conservative wing of the Catholic Church in the West to understand that the modern democratic state is rapidly emerging as the enemy of the Church and to adjust its rhetoric accordingly.
Just a general note based off your post; I think there is no governmental system that is ideal. There are good democracies and bad democracies. Good monarchies and bad monarchies. However, I think democracy is inherently flawed and doomed to fail. Monarchy does have certain advantages.