« IMMORTALE DEI ». — This is one of the great encyclicals of Leone XIII (19 Nov. 1885), in which, taking up again the principles of Gregorio XVI (encyclical Mirari vos) and Pio IX (Sillabo, encyclical Quanta cura), he sets forth the doctrine concerning the reciprocal rights and duties of the Church and the State and the liberties claimed by modern peoples; above all, he establishes for the first time the limits within which Catholics may lend their support to the claims of peoples and to the pretensions of the State.
The ideas put forward by the liberal Catholics at the Congress of Malines (1863) had already received a reserved and private response from the Supreme Pontiff Pio IX through a letter from card. Antonelli; this clarification, however, did not in the least slow the expansion and threat of liberalism. A new condemnation was demanded by circumstances themselves. The encyclical Quanta cura of 8 Dec. 1864 admirably fulfilled this task: liberal ideas were condemned with such clarity that even their own proponents had to abandon the struggle based on equivocation. The error was brought into its proper light through the explicit condemnation of naturalism; yet liberal tendencies did not disappear entirely and continued here and there in speeches, newspapers, and journals. Although they did not take the form of a doctrinal system, these ideas provoked dissension among Catholics in nearly all the European nations. Leone XIII, in the encyclical Nobilissima Gallorum gens (1884), deplored these harmful divisions, connected with bitter controversies, and invited the faithful to unite in the defense of the greater interests of religion. In the same spirit he wrote to the Spanish bishops (Cum multa sint, 1884), so that the religious question would not be confused with the dynastic rivalries between the Carlists and the supporters of the constitution. This appeal was not received favorably. Moreover, in France, Univers did not cease criticizing the practical tendencies of the new Pontiff; in Spain, Siglo censured the manner of acting of the nuncio and of the Holy See. In Rome itself, the ideas of conciliation were attacked. The articles that appeared in Spain and Rome were openly disapproved by the Holy See. Card. Pitra, however, when questioned about the significance of this censure, replied by defending the authors who had been censured. To put an end to all these disputes and divisions, Leone XIII intervened with a doctrinal document: the encyclical I. D., which expounds
the fundamental principles governing relations between the modern Catholic State and the Church. One of the unifying elements of the State is authority, which, although it can originate only from God (Rom. 13:2), nevertheless takes shape in various forms of government which, if they follow the law of divine justice, cannot be condemned by the Church. Corresponding to this divine origin is the obligation of peoples to submit to legitimate authority, without resorting to revolt (Rom. 13:2). This obligation is founded on the natural law that impels man toward society and toward due reverence for the divine Majesty. It is an obligation of religion that must be felt not only by the individual but also by society as a whole, which can in no way act as though God did not exist, but must promote the true religion in every way. Between the two societies, each sovereign within its own jurisdiction, there must therefore be not struggle but harmony; moreover, the ultimate and remote end of both perfect societies coincides: the attainment of humanity’s true good. This concord, the supreme law of the Middle Ages, was shattered by the atheist State, by the unlimited freedom of thought, speech, and the press, and by the absolute equality of all forms of worship, with harmful consequences for the education of youth and peoples. It does not follow from this, however, that the Church is hostile to progress or rejects the modern State, since she has always been the forerunner of the development of every cultural and social form whose aim is the general welfare; she rejects only those doctrines which, under the pretext of freedom, open to peoples the way to every form of license and servitude. In particular, freedom of worship can be tolerated only with a view to some greater good that may come to the Church from II. Ecclesiastical authority has never condemned free discussion of purely political problems. The conduct of Catholics in such matters, however, must always conform to the directives of the Holy See and of the bishops.