As the name implies, Modernism is an ideology by which religious truths, and especially Catholic teachings, are derived and interpreted in accordance with personal religious experience, under the influence of the spirit of the current age. First emerging in the late 19th and early 20th centuries, Modernism was condemned by Pope St. Pius X in 1907. It resurfaced as part of a powerful accommodationist trend in the years following the Second Vatican Council, significantly weakening the Church’s response to modern secularism.In addition to the brief technical definition of the original heresy provided by Fr. John Hardon in our Catholic Dictionary, it is important to start with a good contemporary introduction to the prevailing attitudes of Modernism as they may be observed today.Next, a brief historical survey of the progress of Modernism is very useful in seeing how it developed, how the Church responded, and how it has reemerged again in our own times. This will familiarize you not only with the general currents of thought but specific figures and their ideas.Finally, while the Church has been combating Modernism within her own ranks for the past two generations, particularly in universities and seminaries, the essential explanation of Modernism was provided by Pius X, who called it “the synthesis of all heresies” in his encyclical Pascendi Dominici Gregis.
If you only have time to look at three things, LOOK AT THESE.
- Manifestations of Modernism
- Under the Ban: Modernism, Then and Now
- Pope St. Pius X On the Doctrine of the Modernists (Pascendi)
And if you've got more time...
Two months before Pope St. Pius X promulgated his condemnation of Modernism in Pascendi, the Holy Office had issued a syllabus of 65 widespread modern errors in the document Lamentabili sane. While the simple enumeration of errors has gone out of fashion in recent years (presumably in part because the brevity of expression does not permit a significant exploration of the relevant problems), Lamentabili is of particular value both because of the unifying background the Pope later provided in his encyclical, and because many of the listed ideas are so recognizable today, despite being formulated over a century ago.
A search on CatholicCulture.org for “Modernism” brings up a wealth of other materials which may be of interest for further research.