Where did Roman Catholicism connect modern heresies with the Reformation? Protestant theologian R. C. Sproul, in his series Contemporary Theology, comments on Rome's view of the connection between the Reformation and modern heresies:


  In the latter part of the 19th century, growing out of Vatican I, in the Roman Catholic Church the charge was made that all modern heresies (humanism, pragmatism, existentialism were listed and cited specifically) have their roots in the Protestant Reformation.  That was the Roman Catholic Church's judgment at the end of the 19th century about the chaos in Christendom. ("Background to Contemporary Theology," 5:30)


This certainly sounds like something that Roman Catholicism (and many impartial observers) would accept.  However, I looked in two documents of Vatican I (Dei Filius and Pastor aeternus) and didn't see anything like this.  So:

Did an official outlet of the Roman Catholic Church actually make such a statement in the late 19th century?  Were heresies like humanism and existentialism specifically mentioned as being the result of the Reformation?  Or are such statements only found in the writings of Catholic theologians and not the church itself?
Pope St. Pius X mentions Protestantism in §13, §25, and §§38-39 of Pascendi Dominici gregis,* his 1907 encyclical condemning Modernism, "the synthesis of all heresies" (§39). For example, at the end of §39, "Modernism and All the Heresies," he writes:


  …by how many roads Modernism leads to the annihilation of all religion. The first step in this direction was taken by Protestantism; the second is made by Modernism; the next will plunge headlong into atheism.


The idea of "steps" from modernism to atheism is illustrated, albeit in a Fundamentalist Protestant context, in "The Descent of the Modernists" by E. J. Pace, Christian Cartoons, 1922:



*Here is some audio of Fr. Thwaites, SJ, reading Pascendi: part 1, part 2, part 3