Pius X: "Protestantism as proudly called by its founders, is the sum of all the heresies, that have been before it, after it, and that could still be born to slaughter the souls"

On a web page entitled, Martin Luther: The greatest heretic in human history comes the following quote from Pope Pius X:  

“Protestantism as proudly called by its founders, is the sum of all the heresies, that have been before it, after it, and that could still be born to slaughter the souls” -Pius X

I was curious to see this quote in its original context, especially in light of the current Pope and the trend in ecumenism the Magisterium has engaged in since the twentieth century. For instance, see my post from a few years ago: Pope Francis and Martin Luther. While many of Rome's defenders battle in cyber space to stomp out the "Protestant Revolt," Pope Francis willingly received a statue of Luther at the Vatican and is saying things like, "With gratitude we acknowledge that the Reformation helped give greater centrality to sacred Scripture in the Church’s life." If you were a faithful Roman Catholic between 1903 and 1914, Pope Pius X seems like he's saying something a bit different about the Reformation than Pope Francis in the twenty-first century. Let's take a look at the quote from Pius X and make sure it says what it's purported to say.    

 

Documentation

The web page in which I found this quote does not provide a reference, nor did any of the others I came across in my cursory search with this exact wording. However, there are other versions of the quote that offered up helpful clues:   

"Protestantism, or Reformed religion, as proudly called by its founders, is the sum of all heresies that have been before it, that have been after it, and that still could be born to slaughter souls." St. Pius X, ora pro nobis. (link)

This same catechism (p. 398) states “Protestantism * * * is the sum of all Heresies. The most monstrous congeries of errors, both private and individual, and enfolds all heresies.” (link)

“Protestantism, or the reformed religion, as its founders haughtily call it, is the sum of all heresies that ever existed before it, that have arisen since, or that may arise hereafter for the ruin of souls" (link)

From these texts I was able to determine the primary source: Compendio della dottrina cristiana prescritto da sua Santita Papa Pio X. As one of the texts above states, this was a 1905 Catechism by Pope Pius X.  The quote is found on page 398 of the 1906 edition. 

Context

128. Fra le altre, vanno tristamente famose le eresie: di Sabellio, che impugnò il dogma della SS. Trinità; di Manete, che negò l'Unità di Dio, ed ammise nell'uomo due anime; di Ario, che non volle riconoscere la Divinità di N. S. Gesù Cristo; di Nestorio, che negò a Maria SSma la sua eccelsa qualità di Madre di Dio, e distinse in Gesù Cristo due persone; di Eutiche, il quale in Gesù Cristo non ammise che una sola natura; di Macedonio, che combattè la divinità dello Spirito Santo; di Pelagio, che intaccò il dogma del peccato originale e della necessità della grazia; degli Iconoclasti, che ripudiarono il culto delle Sacre Imagini e delle Reliquie dei Santi; di Berengario, che disdisse la presenza reale di N. S. Gesù Cristo nel SS. Sacramento; di Giovanni Hus, che negò il primato di S. Pietro e del Romano Pontefice; e finalmente la grande eresia del Protestantesimo (sec. XVI), prodotta e divulgata principalmente da Lutero e da Calvino. Questi novatori, col respingere la Tradizione divina riducendo tutta la rivelazione alla S. Scrittura, e col sottrarre la S. Scrittura medesima al legittimo magistero della Chiesa, per darla insensatamente alla libera interpretazione dello spirito privato di ciascheduno, demolirono tutti i fondamenti della fede, esposero i Libri Santi alla profanazione della presunzione e dell'ignoranza, ed aprirono l'adito a tutti gli errori.

129. Il protestantesimo o religione riformata, come orgogliosamente la chiamarono i suoi fondatori, è la somma di tutte le eresie, che furono prima di esso, che sono state dopo, e che potranno nascere ancora a fare strage delle anime.

Conclusion

Yes, the quote says Protestantism is the sum of all heresies that have been before it, that have been after it and that it's a soul killer. The quote is found in an appendix to the Catechism which discusses church history (Breve Storia Della Religione). In #128 (above), Luther and Calvin are specifically singled out for rejecting "divine Tradition" "reducing all revelation to Scripture," and interpreting Scripture without the Roman Magisterium. The quote then follows in #129.  It's interesting that this Catechism is found in various places online (translated into English), but this section does not appear (see, for instance, EWTN's version and this print version). The 1905 Catechism was revised and rereleased in 1912. "The history of the Christian religion" appendix section does occur in the revision, but it appears the appendices are left off at times.  I don't suspect any nefarious purposeful deletions. Rather, it appears the Catechism section has more pragmatic value. 

The Catechism also has some other interesting tidbits: 

Q. What should a Christian do who has been given a Bible by a Protestant or by an agent of the Protestants? A Christian to whom a Bible has been offered by a Protestant or an agent of the Protestants should reject it with disgust, because it is forbidden by the Church. If it was accepted by inadvertence, it must be burnt as soon as possible or handed in to the Parish Priest.

D. Che dovrebbe fare il cristiano se gli venisse offerta la Bibbia da un protestante o da qualche emissario dei protestanti? R. Se ad un cristiano venisse offerta la Bibbia da un protestante, o da qualche emissario dei protestanti, egli dovrebbe rigettarla con orrore, perché proibita dalla Chiesa; che se l'avesse ricevuta senza badarvi, dovrebbe tosto gettarla alle fiamme, o consegnarla al proprio parroco.[source]

Q. Why does the Church forbid Protestant Bibles? A. The Church forbids Protestant Bibles because, either they have been altered and contain errors, or not having her approbation and footnotes explaining the obscure meanings, they may be harmful to the Faith. It is for that same reason that the Church even forbids translations of the Holy Scriptures already approved by her which have been reprinted without the footnotes approved by her.

D. Perché la Chiesa proibisce le Bibbie protestanti? R. La Chiesa proibisce la Bibbie protestanti perché o sono alterate e contengono errori, oppure, mancando della sua approvazione e delle note dichiarative dei sensi oscuri, possono nuocere alla Fede. Per questo la Chiesa proibisce eziandio le traduzioni della Sacra Scrittura già approvate da essa, ma ristampate senza le spiegazioni dalla medesima approvate. [source]

Pope Pius was not tolerant of ecumenism towards Protestants. He lumped all Protestants in with "modernism," that movement of liberalism within theology that infiltrated the ivory towers of academia (philosophy, history, sciences), most particularly Roman Catholic scholarship. Protestantism, according to Pius X, was that movement that ushered in the destruction of religion. Pius also called modernism the "sum" or "synthesis" of all heresies. Despite these attributes, J.N.D. Kelly refers to him as "deeply conservative" and "one of the most constructive reforming popes." Kelly also calls him "A man of transparent goodness and humility" [The Oxford Dictionary of Popes, (New York: Oxford University Press, 1986, 314].