Motives of Credibility: The Growth of the Church

The reader who surveys the New Testament could be forgiven for thinking the growth of the Church in the first century was a series of explosive mass conversions. A post-Ascension community of about 120 persons (cf. Acts 1:15), the Church in swift order added about 3,000 after St. Peter’s Pentecost homily (cf. Acts 2:41). Not long after, the total number of Christians jumped to about 5,000 (cf. Acts 4:4). By the conclusion of the Book of Acts, Christian missionaries won converts among a diverse variety of peoples of the Near East, Africa, Asia Minor, Greece, and even Rome. The letters of St. Paul further suggest that Christian communities popped up throughout the Roman Empire, practically overnight.

It must have appeared that way to the earliest Christians. In a few short decades, a fledgling religious movement that seemed ready for extinction after the death of its messianic leader had made a remarkable turnaround, spreading in every geographic direction from its birthplace in Judea. Its adherents claimed their leader to be not only risen from the dead but literally God Himself, the eternal Logos. As witnessed at Pentecost, men and women both within and without the empire heard and believed that Gospel (cf. Acts 2:5-42).

Yet those dramatic events — even if historically accurate, and there is good reason to believe they are — may be somewhat deceiving. In The Rise of Christianity: A Sociologist Reconsiders History (1996), Rodney Stark, relying on the work of many other scholars, speculates that in A.D. 40, less than a decade after Christ’s Resurrection, there were around 1,000 Christians, amounting to 0.0017 percent of the population of the 60-million-strong Roman Empire. By the turn of the first century, Stark projects, there were fewer than 8,000 Christians, and by the middle of the second century a little over 40,000. As late as the middle of the third century, the theologian Origen admitted that Christians comprised “just a few” of the imperial population.

And then, remarkably, only six decades after Origen’s death, Christians were so numerous — probably about ten percent of the population — that the Emperor Constantine found it expedient to embrace the Church. Within another 50 years, Stark estimates, Christians likely represented a slim majority of the empire. “How did a tiny and obscure messianic movement from the edge of the Roman Empire dislodge classical paganism and become the dominant faith of Western civilization?” he asks. His (empirically based academic) answer is that Christianity offered a better and more secure way of life to its followers, one that spread through natural social networks. Christians exemplified an attractive degree of virtue, including a willingness to endure martyrdom, that appealed to people across class and culture. A consistent growth rate of approximately 40 percent per decade eventually resulted in a majority-Christian empire.

The Catechism of the Catholic Church teaches that the growth of Christianity across history is one of several motives of credibility, “external proofs” of God’s Revelation adapted to the intelligence of everyone, “joined to the internal helps of the Holy Spirit” (no. 156). Even with Stark’s compelling analysis, the expansion of the Church in the early centuries seems improbable, a “marvelous propagation,” as the First Vatican Council calls it (Dei Filius, no. 3). Fr. Réginald Garrigou-Lagrange, O.P., observes that Christianity spread despite significant impediments: worshiping a God who was ignominiously executed; prohibitions of widely accepted practices, such as contraception, abortion, extramarital sex, and exposure of infants; and, of course, persecution. Moreover, it did not spread by oratorical eloquence or worldly sagacity. St. Paul acknowledges that he proclaimed the testimony of God not “in lofty words or wisdom” but in “weakness and in much fear and trembling,” preaching Jesus Christ crucified, “a stumbling block to Jews and folly to Gentiles” (1 Cor. 1:18-2:5). Accompanying this preaching were, of course, many miracles, as I describe in my previous two columns (Nov. 2025 and Jan.-Feb. 2026).

St. Augustine in The City of God describes the odds against the perpetuation of the Christian religion:

The actual manner in which the world came to this belief turns out to be even more incredible. There were just a few men, the merest handful, untrained in the liberal arts, completely uneducated, as far as pagan philosophy is concerned, with no knowledge of literature, no equipment in logic, no trappings of rhetoric. And Christ sent them out as fishermen with the nets of faith into the sea of this world; and in this way he caught all those fish of every kind.

We can add to that list of obstacles the fact that Jesus’ 12 Apostles, save Judas and St. John, were martyred, likely within a few decades of His Ascension. Moreover, between A.D. 62 and 66, arguably the three most important leaders of the early Church — St. James, bishop of Jerusalem; St. Paul; and St. Peter — were killed. Despite this organizational decapitation, the Church kept growing, surviving subsequent periods of violent persecution under Emperors Nero and Domitian (first century), Decius (third century), and Diocletius and Julian the Apostate (fourth century). Indeed, until the fourth century, the majority of the bishops of Rome were martyred.

The victory of the Church over the most powerful empire of the ancient world is certainly a remarkable feat, one that might, on its own, suffice as demonstration of divine approbation. But the Church has weathered many other treacherous moments in her two-millennia history, during which it appeared she might wither and die, as have so many other religious bodies. As St. Thomas Aquinas observes in Summa Contra Gentiles, “Such a wondrous conversion of the world to the Christian faith is a most indubitable proof that such signs did take place.” Let’s consider some of the most important and impressive of these historical moments.

The Islamic Catastrophe

“No event during the first thousand years of Christian history was more unexpected, calamitous, and consequential than the rise of Islam,” writes historian Robert Louis Wilken in The First Thousand Years: A Global History of Christianity (2012). In less than a decade during the 630s, three of the most important cities to the Byzantine Empire and the early Church — Damascus, Alexandria, and Jerusalem — surrendered to Muslim Arab armies. By the early eighth century, Muslims had conquered all of North Africa and Spain, and in 717 they almost captured Constantinople, the greatest of all Christian cities. Only that rebuttal, coupled with a Frankish victory over Muslims at Tours in 732, prevented what might otherwise have been the destruction of the Church, given that at the time the majority of Christians had come under Muslim rule. Everywhere Islam reigned, Christianity went into slow decline; in some places, such as present-day Libya, Algeria, Tunisia, and Morocco, indigenous Christianity disappeared altogether by the 12th century.

Some historians assess that if the crusades of the 11th and 12th centuries had not temporarily distracted the various Muslim kingdoms of the Near East, Muslim armies might very well have overrun Constantinople much earlier and subsequently conquered a weak and fractured Christendom. Though the crusades ultimately failed, the Reconquista — a centuries-long series of wars between Christians and Muslims on the Iberian Peninsula — eventually succeeded in securing the faith there. Yet not long after this defeat in southern Spain in 1492, Muslim forces were again victorious as the Ottoman Empire routed the Hungarians at the Battle of Mohács in 1526 and besieged Vienna, the gateway to western Europe, in 1529. If the Holy Roman Empire had not defeated the Turks at Vienna, it is possible the Church might have gone into decline and eventually died everywhere.

A Tragedious Reformation

Contemporaneous to Muslim incursions deep into central Europe, the Protestant Reformation represented another threat to the existence of the Catholic Church. What began as a theological dispute between a German Augustinian monk and ecclesial authorities over the exploitative sale of indulgences metastasized into a continent-wide battle over the future of Christianity. As the (possibly apocryphal) story goes, Martin Luther nailed his 95 theses to the door of a church in Wittenberg in 1517; four years later, he was debating prominent Catholic clerics at the Diet of Worms before Charles V, the Holy Roman Emperor. Luther’s blockbuster pamphlet To the Christian Nobility of the German Nation persuaded many across the empire to initiate Lutheran reforms. By 1531 two-thirds of imperial cities had joined the Lutheran cause, as had many German principalities. In 1523 Swiss priest Ulrich Zwingli persuaded the city councilmen of Zurich to take the management of Church affairs into their own hands. In the 1530s Geneva welcomed the French Protestant theologian John Calvin to reform their Church.

Protestant ideas soon spread far beyond the Holy Roman Empire. In the 1530s King Henry VIII’s England, for centuries a bastion of Catholic devotion, enacted a series of Lutheran-influenced reforms that severed the English Church from Rome and dissolved 825 religious houses of monks, friars, and nuns. That same decade, Denmark, Norway, and Sweden also went Lutheran. By the mid-16th century, even a significant percentage of the nobility of the Polish-Lithuanian Commonwealth had adopted Calvinism. In the 1560s Scotland, too, went Calvinist. Within a half-century of Luther’s original protest, half of Catholic Christendom was effectively gone. Rebellious troops of the Holy Roman Empire even sacked Rome in 1527, with Lutheran soldiers defacing the Vatican, holding mock Catholic ceremonies, and even kidnapping Pope Clement VII.

Nevertheless, the Catholic Church persevered. The same year as the Diet of Worms, Spanish soldiers vanquished the Aztec Empire in Mexico; ten years later, the Virgin Mary appeared to Aztec peasant Juan Diego Cuauhtlatoatzin and performed several miracles. Within less than a decade, eight million indigenous Mexicans were baptized. Elsewhere in the Americas, Spanish, Portuguese, and French missionaries over the next two centuries converted millions more indigenous peoples from northern Canada to Tierra del Fuego. In Europe, what we now call the Counter-Reformation reinvigorated Catholic faith and practice, recovered Poland for the Church, and, through the persuasive witness of such bishops as Francis de Sales and Robert Bellarmine, won back thousands of Protestants. An alliance of Catholic states organized by Pope Pius V, called the Holy League, defeated the Ottomans at the 1571 naval battle of Lepanto, protecting Catholic Christianity’s southern flank — and, indirectly, all Protestantism, too — from yet another Muslim threat.

France Falls, the Papacy Plummets

The Catholic Church in France is often titled La fille aînée de l’Église (the Eldest Daughter of the Church), and history supplies many reasons for this honorific. After Joan of Arc helped her nation expel English armies from its ancestral territories in the 15th century, French Catholics held strong during the Reformation and sent missionaries (and saints) across the world. Yet the opulence and seeming incompetence of the Church-aligned French monarchy and nobility — coupled with a debilitating economic crisis in the 1780s — engendered resentment and anger, provoking the storming of the Bastille in 1789. The French Revolution accelerated in the 1790s, not only toppling the monarchy but ravaging the Church. Religious orders were suppressed, and clerics publicly executed. In the September Massacres of 1792 alone, 1,400 people, including 225 priests and bishops, were killed. Approximately 30,000 priests fled the country. In 1798 a French army entered Rome and captured Pope Pius VI.

Though Napoleon’s ascension to power in 1799 brought some respite to persecuted French Catholics, it also led to the 1801 Concordat with Rome, which solidified government seizure of ecclesial property, clergy salaried by the state, and government nomination of bishops. The Church in France was now effectively a department of state. “The church had never before experienced such a catastrophe as the French Revolution,” writes Fr. John Vidmar, O.P., in The Catholic Church Through the Ages: A History (2005). He notes that after another pope was captured and imprisoned by French forces in 1809, the papacy lost political influence not just in France but all Catholic Europe.

Yet again, the Church in France, and all Europe, survived. Mary’s appearance at Lourdes in 1858 reinvigorated the faith not only of French Catholics but the faithful worldwide, confirming the recently promulgated doctrine of the Immaculate Conception. Germany, the very heart of the Reformation, experienced a remarkable Catholic revival in the 19th and early 20th centuries; by the 1920s it boasted 20,000 priests for 20 million Catholics. Elsewhere, Catholic immigration and missionary activity in the Americas, Africa, and Asia in the 19th century dramatically increased the global Catholic population. As early as 1850, the Catholic Church was the largest single religious institution in the United States; by 1900, about one-sixth of the nation was Catholic.

The Fascist & Communist Perils

In the 20th century, the dual threats of fascism and communism loomed over the future of the Church. In 1933 Adolf Hitler, a baptized Catholic, declared, “One is either a German or a Christian. You cannot be both.” His National Socialist German Workers’ Party imprisoned or exiled priests, murdering 2,000 at the Dachau concentration camp alone, while another 2,700 were executed in Nazi-occupied Poland. Catholic education and media (there were 400 daily German Catholic newspapers in 1933) went into steep decline. By 1942, with practically all Europe under the control of the Nazis and their allies, the future of the Church seemed dim.

After the defeat of the Nazis in 1945, atheist Soviet communists, who had been persecuting Christians since the Russian Revolution, suppressed the Church across the nations of the Warsaw Pact, including East Germany, Poland, Hungary, and Czechoslovakia. The Soviet intelligence arm, the KGB, actively sought to subvert the Church, not only within Warsaw Pact countries but across the world. “How many divisions does the pope have?” Josef Stalin is said to have mockingly asked, intimating the seeming irrelevance of the Church. Yet, less than 40 years after Stalin’s death, the moral witness of the Church was central to communism’s demise across Eastern Europe. A Polish pope drew millions to a single Mass in Krakow in 1979. In a great irony, Svetlana Alliluyeva, Stalin’s youngest child and only daughter, converted to Catholicism in 1982.

Objections

Let us consider some objections to the growth of the Church as a motive of credibility. One is that other religions have also spread across the world, with Islam, Hinduism, Buddhism, and Mormonism among the most prolific. Hinduism can be dismissed on the grounds that it is hardly universal, given that 94 percent of its adherents reside in India. Where it is practiced outside India, it is almost exclusively by people of Indian heritage. Buddhism is practiced by a more varied group of peoples, though 98 percent of them are exclusive to the Asia-Pacific region. Most of its missionary growth occurred 1,500 years ago.

Islam presents a significant rebuttal to the “growth” motive of credibility. After Christianity, it is the most practiced religion in the world, and it is almost as universal as the Catholic Church, even if the large majority of Muslims reside in North Africa and Asia. Aquinas, however, notes that Muhammad spread his religion via “bestial men” and “force of arms” to compel others to submit to his creed. Fr. Garrigou-Lagrange likewise notes that Islam was “propagated by the authority of rulers, using all sorts of human assistance, like violence, shrewdness, honors, wealth, and the coaxing of illicit pleasures.” And as historian Christian C. Sahner explains in Christian Martyrs Under Islam: Religious Violence and the Making of the Muslim World (2018), after conquering a majority of the Christian world, Muslim rulers took progressively more coercive measures to persuade local populations to embrace Islam, imposing a tax on non-Muslims, prohibiting Christian men from marrying Muslim women, and threatening to execute apostates from Islam. To this day, it is illegal to convert from Islam to Christianity (or any other faith, for that matter) in 19 Muslim-majority countries.

Finally, there is the odd case of the Church of Jesus Christ of Latter-Day Saints (LDS), otherwise known as the Mormons. It’s true that Mormons seem to be practically everywhere — they’ve appeared at my door in Northern Virginia and when I lived in Thailand and Panama. There are LDS churches in 180 countries and territories. Nevertheless, this universality is undermined by the fact that every single president of the Church has been an American, as were, until recent decades, all members of the Quorum of the Twelve Apostles. Though persecution is part of the LDS origin story (its founder, Joseph Smith, and his brother Hyrum were killed in Carthage, Illinois, in 1844 by a mob fearing growing LDS political power and allegations of polygamy), the church today refrains from conducting missionary activity in countries where it is not welcome. Also problematic is the LDS claim that the Christian Church fell into immediate apostasy after the age of the Apostles, a frankly preposterous claim given the incredible details described above.

Let’s briefly consider one more objection, offered by the great 18th-century English historian Edward Gibbon in The History of the Decline and Fall of the Roman Empire. Gibbon asserts that Christianity experienced incredible growth in the early centuries not because of divine approbation but because of, among other things, the “intolerant zeal” of Christians, the doctrine of a future life, and “pure and austere morals.” Though there is no denying the zeal of the early Christians, there were plenty of zealous Jews and pagans at the time as well, as evidenced by the significant persecution the Church suffered from the very beginning. There must have been, says Fr. Garrigou-Lagrange, evident truths that persuaded converts to believe the Christian Gospel. Moreover, he argues, “The promise of a future life does not suffice without the special aid of God.” There were plenty of other contemporaneous religions and philosophical systems that also taught the immortality of the soul yet failed to spread or survive. Finally, the morality of the early Christians impressed but also flummoxed, especially “[pagan] men of degenerate morals” who saw in the Church the upending of the old Roman way of life.

Over the past 2,000 years, empires have risen and fallen, but the Catholic Church remains. She is the oldest continuous institution on the planet and claims over a billion adherents. As Catholic theologian Lawrence Feingold writes in Faith Comes from What Is Heard: An Introduction to Fundamental Theology (2016):

The universal spread and continuity of the Catholic Church — which professes the same holy faith and exhibits the same sacramental form of government based on apostolic succession through twenty centuries, with great numbers of persons living that holy life — is a kind of miracle visible to all generations, including our own…. That a society expand vigorously in its beginnings is natural, but that it do so especially in the midst of the most tremendous persecutions is miraculous.

And the Church is still growing, in places more or less indifferent to the Catholic faith and in others openly hostile. Today there are some 280 million Catholics in Africa; in secular France, where Catholicism has long been thought to be on its way to irrelevance, the number of adult confirmations doubled between 2022 and 2024, jumping again by 45 percent in 2025. Despite decades of communist persecution, there are seven million Catholics in Vietnam and ten million in China. Brutal Islamic persecution earlier this century could not extinguish the Church in Iraq or Syria.

As it was almost 2,000 years ago, the Church is growing, though her methods of propagation might seem weak in the eyes of the world. She spreads not by violence or the promise of delights but by humble moral example, preaching, and miracles. Until Jesus returns, there’s good reason to believe she always will.

©2026 New Oxford Review. All Rights Reserved.

To submit a Letter to the Editor, click here.