His Holiness, Pope Leo XIII
Apostolic Letter to Cardinal Pietro Respighi, Vicar General of Rome
On Protestant Proselytism in Rome (1900)
Apostolic Letter of His Holiness Pope Leo XIII, in which he laments and condemns the preaching and proselytism of Protestants in the city of Rome, Italy.
To M. Pietro Cardinal Respighi, our Vicar General,
Already, from the first moments of Our Pontificate, We had to indicate, as one of the most deplorable harm that is the change in the order of things in this capital of the Catholic world, the ardent proselytism of heresy and, consequently, the peril which the Faith of Our people was exposed to. And on this subject, We having put forward to Our Cardinal Vicar , We have on numerous occasions imparted exhortations, counsels and warnings to the faithful, to warn them against the multiple attempts that sects of all kinds, coming from foreign lands, would exercise here under the umbrella of public laws, in order to spread in the souls of the faithful the poison of denial and error.
However, if on the one hand, We are happy to recognize that Our word, assisted by uninterrupted attention, did not fail to yield good results, on the other hand, We are constrained to confess that — the boldness of the enemies of the Catholic religion having redoubled, thanks to the support that came to them from outside — the evil, far from diminishing, went on increasing, especially in these latter times. It is thus necessary, Lord Cardinal, to revisit this most unpleasant and important subject, which is so intimately linked to the duties and to the rights of Our apostolic ministry and to the loving and paternal love We feel towards Our people of Rome.
It is now well known to everyone by the evidence of the facts that the plan conceived by the heretical sects, multiform emanations of Protestantism, is to raise the standard of discord and religious rebellion in the peninsula [of Italy], but mostly in this noble city [of Rome] which God Himself, admirably ordaining the events, established as the center of this fecund and sublime unity, the object of which was the prayer addressed by our divine Savior to His heavenly Father (John 17:11,21), which was jealously guarded by the Popes, even unto the price of their life, despite the oppositions of men and the vicissitudes of time. After having destroyed in their respective homeland, by opposite and discordant systems, the venerable and ancient beliefs that were part of the sacred deposit of revelation; after having scattered the icy breath of doubt in the souls of their spectators, of division and incredulity — immense ruin that We deplore and of which We are touched by compassion in the bottom of Our heart, for We see in each of these creatures the sons of the same Father, redeemed by the same Blood — these sects have thus introduced themselves into the chosen vineyard of the Lord, with the objective to pursue their disastrous task. Not being able to count on the strength of truth, they reap the benefit, in order to extinguish or at least to reduce the Catholic faith in souls, in the young and helpless, the culturally inadequate, the distressed and the needy, simple people who are accessible to flatteries, to lures, and to seductions.
Being made aware of this fact, before anything We suffer the need to confess, as We have done so on other occasions, just how exasperating is the condition imposed upon the head of the Catholic Church, forced to observe the free and progressive development of the heresy in this holy city, from which must shine forth on the world the light of truth and of good example, and which should be the respected See of the Vicar of Jesus Christ. As if this didn’t suffice, to corrupt the mind and heart of the people, from a torrent of unwholesome doctrines and depravations that spring forth with impunity on a daily basis, from professor’s chairs, from theaters, from newspapers, there had to be addedd to all these causes of perversion the insidious labor of heretical men which, fighting amongst themselves, are but of one accord to inveigh against the Supreme Pontifical Magisterium, the Catholic clergy, and the dogmas of our holy religion, of which they know not the meaning and much less appreciate its august beauty.
From which it follows that the faithful, who, from all regions, even the most remote, flock in pilgrimage to Rome to find comfort to their piety and to their Faith, must remain profoundly saddened as they gaze down on the ground, soaked as it is by the blood of martyrs, invaded by sects of all kinds, whose sole worry is to tear away from the soul of the people this religion that was declared the religion of the state and that is the principal object of their love and worship.
You will thus easily understand, Lord Cardinal, how painful this sad state of affairs is to Our heart and how keen is Our desire to witness the appropriate remedies that will, if not entirely extricate the evil, at least severely diminish its gravity and its bitterness. This is why We were greatly comforted by the founding of a distinguished organization, to which We have Ourselves given the inspiration and impetus and which is called Preservation of the Faith, even more so by the satisfying results that it started to gain, thanks to the inextinguishable zeal of both those who lead it and are part of it.
It is Our wish, Lord Cardinal, counting on your usual and well-known activity, that this salutary work, so well adapted to the present needs, should sustain, reinforce, and propagate to the point of constituting an efficient and powerful defense against the aforementioned peril. First of all, a firm and constant support will have to be supplied by the parochial clergy of Rome; hard-working, zealous, and modest, upon whom the care and responsibility of souls is chiefly incumbent; vitality, strength, and expansion will be further added, thanks to the Catholic laity of this town, which are always ready to bring their intelligent and charitable contributions wherever the interests of religion and the material and moral well-being of their neighbor is at stake.
For everyone, may the principal worry be to strengthen the character of the Catholic people, inspiring noble and holy intentions, at the same time preventing carelessness in which, under the guise of innocent assemblies for young people, conferences for young girls, foreign-language courses, growth of culture, and subsidies to poor families, lies hidden a criminal purpose to insinuate in the minds and hearts the reprobate maxims of heresy.
May all the faithful be thoroughly imbued with this truth that nothing can be more precious to them than this treasure that is their Faith, for which their forefathers confronted without fear, not only miseries and deprivations, but also often violent persecutions and even death. Such a sense of strength cannot but be natural and profound in our population that knows all too well that, not only does the Catholic Church possess the divine seal that distinguishes it as the only true one, the only one which received the promises of life immortal, but has spread again at all times her incomparable blessings on Rome, on Italy, and on all the world, subduing the onslaught of barbarism with the justice of her laws and the meekness of her mores, spreading, as St. Leo the Great (Serm. I, in Natali SS. Petri et Pauli) said so well, the dominion of Christian peace well beyond the explored confines by the Roman eagles, salvaging literature, libraries, intellectual culture, monuments; inspiring all orders of science and art; coming to the aid of the weak, the poor, the oppressed, with the generosity of love and with magnanimity of sacrifice and of heroism.
It is why We nourish the confidence that none of the Romans, who are the most privileged sons of the Catholic Church, will ever want, for any human interest whatsoever, to separate himself from this most tender Mother that, after having given him birth in grace, never ceased to surround him by her most affectionate solicitudes: of which we are also equally persuaded that those generous Catholics who founded and propagated the aforementioned organization called Preservation of the Faith, will never give themselves to respite or rest as long as eternal salvation is in jeopardy, should it be so for one soul, showing thusly by the very fact, if the enemies of the religion are stronger by the quantity of riches, the former will vanquish by the fullness of their charity.
As a token of divine favor for bringing this grave task to a happy end, We grant with all our heart, Lord Cardinal, to the promoters of this pious endeavor and to all those who will favor it, the Apostolic Benediction.
Leo XIII, Pope.
From the Vatican, this 19th day of August, 1900.
 A reference made to the Pontifical Letters addressed to the Cardinal Vicar, on June 26, 1878 and March 25, 1879.