The Leonine encyclicals concerning the place of the Church in the modern world, spanning the years 1878 up until his death in 1902, included Immortale Dei (expounding on the nature of the Christian state) in 1885 (14) and Testem Benevolentiae Nostrae (condemning Americanism) in 1899.
Generally, they adhered to the traditional Catholic teaching on the nature of the state laid down earlier in Immortale Dei, which was issued in 1885.
Las ensenanzas de Leon XIII en la Immortale Dei
seguian el mismo enfoque, aunque sin acudir a la palabra <<laicidad>>.
On Liberalism and Religious Indifferentism (1832), Quanta Cura: On Condemning Certain Errors (1864), Immortale Dei: On the Christian Constitution of States (1885) all reacted against the 'absolutist' notion of freedom portrayed by the French Declaration.
In the Encyclical Immortale Dei (1885) and in Sapientiae Christiana (1890), for instance, Pope Leo XIII had mostly used the distinction to legitimize the respect due by the State to ecclesiastical authority, rather than to condemn the imposition of the Catholic faith in the public sphere.
Pope Leo XIII declared in his 1885 encyclical Immortale Dei
that the church was not committed to any particular form of government and that she could work with all, but he also went on to condemn freedom of religion and freedom of the press as threats to civil society and true religion.
Among the most important encyclicals are: Inscrutabili Dei Consilio, "On the Evils of Society," 1878; Quod Apostolici Muneris, "On the Evils of Socialism," 1878; Aeterni Patris, "On the Restoration of Christian Philosophy," 1879; Arcanum, "On Christian Marriage," 1880; Diuturnum, "On the Origin of Civil Power," 1881; Immortale Dei
, "On the Christian Constitution of the State,"1885; Libertas, "On the Nature of Human Liberty," 1888; Exeunte lam Anno, "On the Right Ordering of Christian Life," 1888; Sapientiae Christianae, "On Christians as Citizens," 1890; Rerum Novarum, "On Capital and Labor," 1891; Graves De Communi Re, "On Christian Democracy," 1901.
Similarly, the fourteen pages devoted to the doctrine of subsidiarity note its origin in late nineteenth and early twentieth century papal encyclicals, especially Immortale Dei
(1885) and Quadragesimo Anno (1931).
While La Piana traces the participation of Catholics in the political realm from the early days of the Republic, he points to a particularly notable papal blessing of sorts for the participation of Catholics in politics with the words of Pope Leo XIII in Immortale Dei (1885): "It is evident that Catholics have just reasons to get into politics; but they must do this, not because they can approve of what is deplorable in the present political institutions of their country, but in order to use those institutions in such a way as to secure the public good, and with the purpose of injecting in all the veins of the State, as a new vital blood, the virtue and influence of the Catholic religion." (p60)
La Piana reinforces this impression by focusing Immortale Dei's influence on the subsequent development of Catholic political parties in Europe, and the subsequent participation of some of those parties in the rise of Fascism.
In Quanta cura (1864) Pius IX repeated Gregory XVI's attack on "the madness that freedom of conscience and of worship is the proper right of every human being and ought to be proclaimed by law and maintained in every rightly constituted society." In 1885 Pope Leo XIII reaffirmed the rejection of religious liberty in Immortale Dei
, an encyclical explicitly focused upon "the Christian constitution of states."