In very recent weeks, a controversy has erupted in Catholic discussions following remarks attributed to Pope Leo XVI in an interview with Crux Now (also reported by LifeSite News). According to these reports, Pope Leo said:
“People want the Church doctrine to change, want attitudes to change. I think we have to change attitudes before we ever change doctrine.”
He also added that, while he finds it “highly unlikely, certainly in the near future, that the Church’s doctrine in terms of what the Church teaches about sexuality, what the Church teaches about marriage … will change.”
Some observers interpret these remarks as suggesting that once cultural or popular “attitudes” shift, doctrine might follow. Others insist the Pope was emphasizing pastoral sensitivity—that attitudes among the faithful must evolve (in understanding, charity, discipline) but that doctrine in its substance remains fixed.
This debate underscores a perennial question in Catholic life: What is doctrine? When and how can it legitimately develop? Is it ever changeable, or only the expression and application?
Warning: Unshakeable Truth of Enduring Doctrine
Introduction: An Age of Confusion
Our moment is marked by a restless call for “change” in every sphere, including religion. Many contemporary voices—even within the Church—speak as if immutable truths of faith could be revised to meet new social expectations. Yet the Catholic Church, entrusted with the deposit of faith by Christ Himself, insists with serene clarity: dogma and doctrine cannot change in their essence. This article draws on the perennial teaching of the Church, as articulated at the Council of Trent, reaffirmed in the Syllabus of Errors (1864), clarified by Saint John Henry Newman’s theory of the development of doctrine, and defended against the heresy of Modernism in Pascendi Dominici Gregis (1907). Together they witness to the same truth: the Church’s doctrinal definitions may develop in expression and depth, but they cannot mutate in substance.
I. Defining Terms: Dogma and Doctrine
The Catholic theological tradition distinguishes dogma from doctrine, though the two are intimately related.
Dogma is a divinely revealed truth solemnly defined by the Church’s Magisterium as binding on all the faithful. Examples include the dogmas of the Trinity, the Incarnation, and the Immaculate Conception. Dogmas require the assent of faith (fides divina et catholica).
Doctrine, more broadly, is any authoritative teaching of the Church regarding faith and morals. Some doctrines are revealed (and thus dogmatic); others are authoritative applications of revealed truth, which nonetheless require religious submission of intellect and will (obsequium religiosum).
Both dogma and doctrine participate in the Church’s deposit of faith, the “faith once for all delivered to the saints” (Jude 1:3). They differ not in origin but in degree of formal definition and the type of assent required. Neither may be overturned without betraying Christ Himself, who is the Truth (John 14:6).
II. The Council of Trent: Defining Immutable Faith
The Council of Trent (1545–1563) met during the Protestant Revolution to clarify and defend Catholic doctrine. Trent declared with unmistakable firmness that Divine Revelation is contained in both Sacred Scripture and Sacred Tradition and that the Church alone is the authentic interpreter of that Revelation.
In its Decree on Justification and other canons, Trent solemnly anathematized anyone who would reject or distort these truths. The Council declared:
“If anyone shall say that it is possible that at some time, given the progress of knowledge, a sense may be assigned to the dogmas propounded by the Church which is different from that which the Church has understood and understands: let him be anathema.”
This canon anticipates later debates about doctrinal development and firmly rejects any idea of essential change. Trent’s authoritative definitions remain binding, for they express truths revealed by God and entrusted to the Magisterium.
III. The Syllabus of Errors: Pius IX’s Prophetic Warning
Three centuries later, Blessed Pius IX confronted the rising tides of rationalism, liberalism, and indifferentism. His Syllabus of Errors (1864) enumerated and condemned propositions that undermined Catholic truth, including the claim that “Divine Revelation is imperfect, and therefore subject to a continuous and indefinite progress.”
This prophetic document insists that dogma does not evolve into something essentially different. While the Church’s understanding can grow in clarity and application, it cannot be altered to accommodate the spirit of the age. The Syllabus thus reinforces the unchanging character of Catholic teaching against pressures that continue to this day.
IV. John Henry Newman and Authentic Development
How, then, are we to understand the Church’s growing articulation of doctrine? Saint John Henry Newman’s seminal Essay on the Development of Christian Doctrine provides the classic Catholic answer. Newman distinguishes authentic development from corruption.
Authentic development occurs when the Church, guided by the Holy Spirit, draws out implicit truths or applies perennial principles to new circumstances. Examples include the explicit definitions of the Trinity at Nicaea or the dogma of the Immaculate Conception. These are not new revelations but organic growth, like an acorn becoming an oak.
By contrast, corruption occurs when the original meaning is contradicted or abandoned. Newman warns that to alter doctrine so that it no longer conveys the apostolic faith is not development but decay. His insight harmonizes with Trent and the Syllabus: the Church may deepen her understanding, but she cannot redefine truth.
V. Pius X and the Condemnation of Modernism
Despite Newman’s careful distinction, the late nineteenth and early twentieth centuries saw the rise of Modernism, a movement claiming that all dogma must adapt to evolving human experience. Pope St. Pius X, in his 1907 encyclical Pascendi Dominici Gregis, denounced Modernism as “the synthesis of all heresies.”
Modernists argued that dogmas are mere symbols of religious feeling, inevitably changing as cultures change. Pius X rejected this outright:
“Dogma is not only able, but ought to evolve and be changed,” they assert— a proposition which We declare to be absolutely false and utterly opposed to the faith.
In the same document, Pius X mandated the Oath against Modernism, requiring clergy and teachers to affirm that the meaning of dogmas remains “perpetually the same.” Far from stifling growth, this protected genuine development as Newman envisioned, while rejecting any mutation of substance.
VI. Unchanging Truth and Living Tradition
Catholic tradition is living, not static. But “living” does not mean “mutable.” Rather, it is the life of the Holy Spirit who “will guide you into all truth” (John 16:13). The Magisterium, as servant of the Word of God, ensures that the faith is handed on “whole and entire” (cf. Dei Verbum 10).
This means that while explanations and pastoral approaches can and do adapt, the content of dogma and the core of doctrine are immutable. To claim otherwise is to imply that God deceives or that truth itself is relative—both blasphemous propositions.
Conclusion: Fidelity Amid the Tempest
The Catholic Church stands as a bulwark against the shifting sands of relativism. From Trent to Pius IX and Pius X, from Newman’s profound insights to the modern Magisterium, the constant teaching is clear: the substance of Catholic dogma and doctrine cannot change. What develops is our penetration of the mystery, our vocabulary, and our pastoral application—not the truth revealed by God.
In an era of doctrinal confusion, Catholics are summoned to deeper study, prayerful fidelity, and courageous witness. As St. Paul exhorted, “Guard the good deposit entrusted to you” (2 Tim 1:14). Only by holding fast to the unchanging faith can we hand on to future generations the treasure once delivered to the saints.