As a linguist and historian, I heartily agree with Grace Spiewak (“Latin is not just for encyclicals. For all Catholics, it is our living history”) on the value of studying Latin or any classical language. But I take issue with conflating Latin with Catholicism writ large.

This is not an antiquarian quibble over words. It represents a mindset and a presumption that the Roman Catholic Church is just now beginning to recognize.

Latin is not the cultural legacy of “all Catholics.” Eastern Catholic churches struggle now more than ever to maintain an identity that the far larger and more prosperous Latin-speaking Roman church once sought to suppress by imposing its customs, liturgy and, yes, language.

Eastern Catholic churches struggle to maintain an identity that the far larger and more prosperous Latin-speaking Roman church once sought to suppress.

His Beatitude Maximos IV Saigh, the patriarch of the Melkite Greek Catholic Church from 1947 until his death in 1967, was the standard-bearer of a struggle over the presumed universality of the church’s use of Latin. At the Second Vatican Council, Patriarch Maximos’s stirring interventions helped lead to the adoption by the Latin church of long-held Eastern Catholic practices. These included the use of the vernacular in public worship; eucharistic concelebration and Communion under both species (i.e., both the consecrated bread and wine); the permanent diaconate; and the establishment of what ultimately became the synods of bishops held periodically in Rome.

Before the opening of the council, Vatican insiders had determined that the proceedings would take place either in classical or modern church Latin. But Patriarch Maximos argued that the exclusive use of Latin reinforced a “ghetto-like insularity.” Was Vatican II to be merely a plenary council of the Latin church or truly ecumenical? In the end, the use of Latin was mandated at the council, but the patriarch was not deterred.

At the first session of the council, on Oct. 23, 1962, Patriarch Maximos gave an electrifying speech that set the tone for the Eastern Catholic battle against the one-sided, Latin-language understanding of the church. He adamantly refused to speak in Latin, referring to it as “the language of the Latin church but not of the Catholic Church” and certainly not of his church. (A detailed account of Patriarch Maximos’s participation in the council can be found in Saba Shofany’s The Melkites at the Vatican Council II).

Worship is something very different than work in the classroom. To be authentic, worship must be in a language people actually speak and understand.

Patriarch Maximos also refused to follow protocol and address “their eminences,” or the cardinals, before “their beatitudes,” or the Eastern patriarchs. In his ecclesiology, the patriarchs, as the heads of local churches, did not take second place to the cardinals, who were but second-rank dignitaries of the Latin church.

Most significant, he urged the West to allow vernacular languages in the liturgy, following the lead of the East, “where every language is, in effect, liturgical.” He concluded, in true Eastern fashion, that the matter should be left to the local churches to decide. No wonder it made international headlines. He was speaking a language that even journalists, baffled by obfuscating “clericalese,” could understand. Patriarch Maximos spoke simply and clearly—and he did so in French.

In any tradition, worship is something very different than work in the classroom; at least it should be. To be authentic, worship must be in a language people actually speak and understand.

Ms. Spiewak writes, “Far from stifling or limiting” ideas, the knowledge of Latin can “reinforce core values of self-motivation, communication and originality.” In fact, the opposite is true. The use of Latin presents serious drawbacks, including its inability to easily and accurately express matters related to the modern apostolate.

It is true that encyclicals are promulgated in Latin, but they do not begin life that way. Pope Francis is fluent in Latin, but when formulating what he intends to be the official teaching of the church, he writes in his native Spanish. Only then is the document handed over to Vatican translators who render it into Latin. The translations that follow are repeatedly checked against Francis’ original to ensure fidelity to the nuances of the Spanish. The fact is that no ancient language can hope to speak with the clarity or immediacy of a modern, native language. Even in Europe, the universality of Latin was always more ideal than real. While claiming to be universal, Latin failed to represent Christianity as it was actually lived on the local level.

I am a priest of the Syriac Maronite Church who has been deeply involved in the effort to fulfill the mandate of Vatican II to restore our tradition to its original integrity. It is a daunting process that includes not only rendering ancient liturgical texts into accessible English but removing entire swaths of interpolated texts imposed from the Latin West.

Meanwhile, it is no overstatement to say that we may be witnessing the disappearance of Christianity from the very lands of its birth. Pope Francis has responded to the crisis with courage that borders on heroism. But the struggle is not his alone. It is the responsibility of all of us to become better informed about the crisis facing Christians of all communions, especially those who look and pray differently than those of the dominant, Western culture.

There are countless benefits that accrue from the discipline and pleasure of learning ancient languages. Authentic worship is not one of them.

The Rev. Joseph P. Amar is a professor emeritus of Syriac and Arabic languages and the Program in Early Christian studies at the University of Notre Dame, near South Bend, Ind.