In a letter to the editor of First Things, my brother Benedict objects to Pierre Manent’s claim that while Western Christianity was born in an imperial form, it “found its form in the nation, or in the plurality of nations once called ‘Christendom,’ then ‘Europe:’”
To me, the nation-state does not mean heroic unity in the face of foreign invasion, but World War I: the destruction of the supranational Danube Empire and the creation by violence and forced emigration of homogenous nation-states. […] For Dante, it was precisely the inability of Christendom to unify under a single emperor, Ottoman-style, that was its downfall. Nothing illustrates the failure of the loose federal Christendom model better than its inability to unite against the external threat of the sultan’s armies. French national interest, Venetian national interest, Hungarian national interest prohibited a united effort, and the result was the Ottoman conquest of the entire Balkan peninsula and untold suffering for its Christian inhabitants.
As the example of Dante shows, Medieval Christendom all the way to the end was inspired by the imperial ideal of a universal temporal order. Virgil can be said to be the “father of Europe,” partly because of his imperial ideal was subsidiarist ideal that left room for local piety. And the Roman Church— from Pope Gelasius’s Famuli vestrae pietatis to Pope Francis’s Laudato Si’— has never given up the ideal of a universal temporal power, corresponding in some way to her universal spiritual power.
The ideal was, however, never fully realized, and was made almost impossible by the forces that brought the Middle Ages to an end. Arguably the estrangement of Byzantium and Rome had already made the ideal of empire unattainable, but it was the Reformation that made even a semi-empire in the West practically impossible. And sadly “French national interest” had an important role in making the Reformation possible, preventing it from being reversed, and preventing the emergence of a post-Reformation empire in the parts of Europe that remained Catholic.
However much the medieval popes and emperors quarreled, they always shared a basically imperial idea of Christendom. The quarrel between Philip the Fair and Boniface VIII on the other hand was quite a different thing: it was (among other things) a quarrel between an imperial and a national ideal of human of common life. This was the beginning of the end of the Medieval Christendom. There followed the Avignon exile of the papacy, and then the conflicts between France and the Habsburgs. If France had supported the emperor in the 30 Years War, it is likely that the Reformation could have been reversed. Even afterwards, “French National Interest” continued to make a semi-empire in Catholic Europe impossible. Charles VI losing the War of Spanish Succession to the French was almost as great a blow to the Holy Roman Empire as Francis II formally dissolving it under the pressure of Napoleonic French aggression, less than a century later. Fittingly, it was Charles VI, who left one of the most beautiful symbolic monuments of the empire: the Karlskirche. I celebrate Mass in the Karlskirche from time to time for Una Voce Austria, and it always makes me reflect on the nature of Christendom.

The Karlskirche
As Friedrich Polleroß has pointed out, the Karlskirche is meant to remind us of the Solomonic Temple, the temples of pagan Rome, Hagia Sophia, and St. Peter’s in the Vatican. The classical portico stands for the heritage of imperial Rome, the two great pillars stand both for the for the pillars of Hercules and for Jachin and Boas. The pillars of Hercules show that the empire is to stretch to the ends of the earth. But Jachin and Boas show that the emperor is the new Solomon; above the classical portico is a dome reminiscent of the cupola of St. Peter’s— the Holy Roman Empire exists for the exaltation of the Holy Roman Church.
Pierre Manent is of course right that the EU is antithetical to the true spirit of Christendom, but it is ironic that he praises French nationalism as conformable with that spirit. Oddly enough, the EU was largely put together by Frenchmen. It is even said that Alexandre Kojève was an influence, after his dream of a Latin (i.e. French) Empire failed to materialize.
Postscript: lest I be accused of Francophobia: France is awesome.