Pagan mysticism, unlike Christianity, produced no comparable moral effect on the societies that practised it. An uncompromising opposition, moreover, has always existed between the genuinely Christian and the pagan spirit: “bear not the yoke with unbelievers. For what participation hath justice with injustice? Or what fellowship hath light with darkness? And what concord hath Christ with Belial? … for you are the temple of the living God” (2 Cor. 6:14–16). The Vatican Council itself teaches that Christian doctrine, in its perfect harmony of things highest and lowest, supernatural and natural, justice and mercy, contemplation and action, old and new, has so profoundly affected the minds and souls of mankind, and so thoroughly renovated society, that it is metaphysically impossible Divine Providence should have permitted so salutary a teaching to rest, from its very origin, on an underlying error.

To conclude the argument of the preceding chapter: (1) the teaching of Christ is distinguished by its perfection, harmony, and sublimity; (2) it was preached with a unique combination of authority, simplicity, humility, unction, and efficacy; and (3) it owed its origin to no merely human source, whether Jewish, pagan philosophical, or Eastern mystical. Such a teaching is, with moral certitude, rightly declared to be supernatural. It has already been shown that man cannot, without supernatural help, discover the whole sum of the truths of natural religion by his own powers; a fortiori, one man alone — Jesus of Nazareth, who never studied in the schools of the learned — could not, without extraordinary help from God, have discovered a body of religious teaching that satisfies so perfectly the deepest aspirations of human nature.

The Testimony of Christ Is Confirmed by the Wonderful Life of the Church

The Vatican Council itself suggests the natural division of this argument: the Church is herself “a perpetual and irrefragable witness” of her own divine mission, on account of (1) her wonderful propagation, her extraordinary sanctity, and her inexhaustible fecundity in every good work; (2) the extraordinary sanctity seen in the constancy of her martyrs and in her spiritual fecundity; and (3) her Catholic unity and her unshaken stability.

Article 1 — The Wonderful Propagation of the Church

The force of this argument lies in the sheer disproportion between the actual propagation of the Christian Faith and the merely natural causes available to explain it — a disproportion shown from a fourfold consideration: (1) the rapidity of Christianity’s diffusion; (2) the grandeur of the result actually obtained; (3) the many and serious obstacles it had to overcome; and (4) the manifest weakness of the natural means at its disposal.

I. The rapid diffusion of Christianity.

(A) Numerically and geographically. We read in Acts that after Pentecost, Peter’s preaching converted three thousand souls in a single day (Acts 2:41), and soon after five thousand more (Acts 4:4); “the multitude of men and women who believed in the Lord was more increased” still further (Acts 5:14). At the martyrdom of St. Stephen, persecution broke out in Jerusalem, and the faithful “were all dispersed through the countries of Judea and Samaria … and they went about preaching the word of God” (Acts 8:1–4); some travelled “as far as Phenice, and Cyprus, and Antioch … and a great number believing, were converted to the Lord” (Acts 11:19–21), and it was at Antioch, after a year of teaching by Barnabas and Saul, that “the disciples were first named Christians” (Acts 11:26). The Apostles went on to found churches throughout the Roman Empire and even beyond its formal boundaries. About thirty years after the Ascension, Peter could write to “the strangers dispersed through Pontus, Galatia, Cappadocia, Asia, and Bithynia” (1 Pet. 1:1); Paul, at about the same time, wrote to the Romans that “your faith is spoken of in the whole world” (Rom. 1:8); and John, writing the Apocalypse toward the end of the first century, addressed “the seven churches which are in Asia” — Ephesus, Smyrna, Pergamus, Thyatira, Sardis, Philadelphia, and Laodicea (Apoc. 1:11). Even before the death of the last Apostle, then, the number of Christians was already very great.

After the death of the Apostles, the faithful continued to multiply. Justin Martyr could declare, about A.D. 150, that there was no race of men, barbarian or Greek, among whom prayers were not offered in the name of the crucified Jesus (Dialogue with Trypho, n. 117); St. Irenaeus, writing at about the same time, testifies to churches already established in Germany, Spain, Gaul, the East, Egypt, Libya, and Judaea (Adversus Haereses, I, 10; III, 3). At the start of the third century, Tertullian could write with pardonable rhetorical flourish that Christians, though “of yesterday,” had already filled every city, island, fortress, town, camp, tribe, guild, the imperial palace itself, the senate, and the forum, leaving the pagans only their temples (Apologeticum, c. 37); and it was said that the greater part of Carthage itself was already Christian (Ad Scapulam, c. 5). Pagan writers confirm the same picture: Tacitus speaks of a “great multitude” of Christians put to death under Nero (Annals, XV, 44), and Pliny the Younger, as governor of Bithynia, reports finding great numbers of Christians there (Epistle 97). Harnack himself admits that by A.D. 300, Christianity already prevailed throughout Asia Minor, Thrace, Cyprus, and Edessa, and had spread widely through Coele-Syria, Egypt, southern and central Italy, proconsular Africa, Numidia, Spain, Greece, and southern Gaul.

(B) Socially. Many early Christians were, certainly, of the common people, fulfilling the prophecy that “to the poor the gospel is preached” (Is. 61:1; cf. Matt. 11:5); St. Paul could write to the Corinthians of how few among them were, by worldly standards, wise, mighty, or noble, “but the foolish things of the world hath God chosen, that he may confound the wise … and the weak things of the world hath God chosen, that he may confound the strong” (1 Cor. 1:26–27). Yet — more remarkably still — men and women of rank, wealth, and learning were converted as well. Among the rich and noble: Sergius Paulus, the Roman proconsul, and Dionysius the Areopagite (Acts 13:12; 17:34); members of Titus Flavius Clemens’s own household (Acts 18:8; 1 Cor. 7:12); St. Cyprian records that under the Emperor Valerian not a few Christians were found even among senators, knights, centurions, and tribunes; and Eusebius, in his Ecclesiastical History, names the wives of illustrious men — Volusia, Marcia, Julia Mammaea, Severa the wife of Philip, the wife and daughter of Diocletian, and the wife of the prefect of Rome under Maxentius — many of whom suffered martyrdom for the Faith. Among the learned: Dionysius the Areopagite, Apollos of Alexandria, Justin, Athenagoras, Aristides, Irenaeus, Tertullian, Cyprian, Clement of Alexandria, Origen, and the whole Alexandrian school. Arnobius records that gifted orators, grammarians, rhetoricians, doctors of law and of medicine, and philosophers exploring the deepest questions all sought out this new Christian teaching, abandoning the doctrines they had formerly held (Adversus Gentes, II, 5). Throughout the first three centuries, in short, Christianity spread with remarkable rapidity across the whole Roman Empire and beyond its frontiers, and was diffused through every level of society at once.

II. This diffusion had, moreover, a wonderful moral effect. Countless men set aside vicious habits, unnatural crimes, and worldly pride, to embrace instead a chaste, humble life of voluntary poverty; representatives of every social condition succeeded, in St. Thomas’s phrase, in “believing things so obscure, achieving things so difficult, and hoping for things so lofty” (Contra Gentiles, I, c. 6). Family life, the dignity of woman, and the condition of slaves were all transformed, and the whole fabric of society was gradually reconstructed in a spirit of charity and justice. St. Justin could write: “those who once delighted in fornication now embrace chastity alone; those of us who practised magic arts have dedicated ourselves to the good and unbegotten God; we who once took most pleasure in the means of increasing our wealth now bring what we have into a common stock … we who hated and destroyed one another … now, after the coming of Christ, live together” (First Apology, n. 14). Lactantius, in a famous passage, describes how the influence of a few words of God could transform the irascible into the gentle, the avaricious into the generous, the man who feared death into one who would despise the cross and the fire, the adulterer into the chaste, the sinner into the innocent — “all wickedness disappears in the waters of regeneration” (Divine Institutes, III, 26). Eusebius bears similar witness regarding the Persians, Scythians, Bactrians, and other peoples once given over to horrible and unnatural vice, now delivered from “the beastly plague of so many evils” by the power of the Gospel (Praeparatio Evangelica, I, 4). Even pagan writers — Pliny the Younger, Lucian in his mocking account of Peregrinus, and the Emperor Julian himself, in Sozomen’s record — could not withhold praise for the virtue and mutual charity of the Christians they observed.

III. The obstacles to be overcome were, at the same time, many and severe. (A) In the acceptance of the doctrine and worship itself: “we preach Christ crucified, unto the Jews indeed a stumblingblock, and unto the Gentiles foolishness” (1 Cor. 1:23). The Jews expected a temporal Messiah, and were unwilling to acknowledge as true God one they themselves had crucified, scandalized as they were by what appeared, from their perspective, His humiliating defeat; nor were they willing to abandon the rites and ceremonies of the Mosaic Law. The Gentiles, for their part, found the whole idea of a suffering, dying God, and of voluntary sacrifice offered by a just and wise man, simply foolish according to the assumptions of pagan philosophy — and, according to pagan piety, idolatrous statues had now to be abandoned, pagan temples overthrown, pagan sacrifices and superstitious practices held in open abhorrence. (B) In the reformation of morals: the whole Christian ethical system was odious to a corrupt pagan society, since it declared open war on cupidity and pride alike; St. John could write, “love not the world, nor the things which are in the world … for all that is in the world, is the concupiscence of the flesh, and the concupiscence of the eyes, and the pride of life” (1 John 2:15–16). (C) In persecution: pagans could readily tolerate any form of religion reconcilable with the general worship then prevailing throughout the Empire, but the Christian religion, which by its very nature excludes every other cult, was for that reason detested; by law, Christians of humble rank were thrown to wild beasts or burned alive, while those of higher rank were, more mercifully, beheaded. The obstacles standing in the way both of accepting Christian teaching and of the moral reformation it demanded were, across three full centuries of intermittent persecution, extremely numerous and severe.

IV. The natural means available for recommending Christianity to the world, meanwhile, were themselves extremely feeble. (A) Neither violent coercion nor the inducement of pleasure was available to the early preachers of the Faith: “the weapons of our warfare are not carnal” (2 Cor. 10:4). (B) Natural eloquence and worldly wisdom, similarly, could avail little. What culture, what training in philosophy, what rhetorical skill did the Apostles themselves actually possess? St. Augustine observes that the world came to believe through a small number of poor, weak, unskilled men, precisely because the Divine power itself, working through witnesses so humanly contemptible, brought about conviction in a wonderful and unmistakable way (De Civitate Dei, XXII, 5). St. Paul says as much of himself, writing to the Corinthians: “when I came to you … I came not in loftiness of speech or of wisdom … I was with you in weakness, and in fear, and in much trembling: and my speech and my preaching was not in the persuasive words of human wisdom, but in shewing of the Spirit and power: that your faith might not stand on the wisdom of men, but on the power of God” (1 Cor. 2:1–5).

Conclusion. The disproportion between the merely natural means available and the actually wonderful propagation of Christianity could hardly be plainer. St. Thomas writes that it would be more wonderful than any miracle if the world, without any miracle at all, had been persuaded by simple and unlearned men to accept doctrines so obscure, to achieve works so difficult, and to cherish hopes so lofty (Contra Gentiles, I, c. 6); and St. Augustine puts the same point with characteristic economy: if you refuse to believe in miracles, then this one great miracle should suffice you — that the whole world came to believe without any (De Civitate Dei, XXII, 5). Such a wonderful conversion of multitudes stands, in effect, as the very seal of God confirming the divinity of the Christian Faith.

Gibbon, in the fifteenth chapter of his Decline and Fall of the Roman Empire, attempts to explain the rapid propagation of Christianity on purely natural grounds. He assigns as intrinsic causes (1) the evident truth of Christian ethics, and the consequent purity of Christian life; (2) the promise of eternal happiness; and (3) the zeal with which Christians preached their Faith as alone true and alone necessary for salvation; and as extrinsic causes (1) the political unity of the Roman Empire; (2) the manifest insufficiency of pagan philosophy; and (3) the eventual conversion of the invading barbarian nations. Against the supposed intrinsic causes it may be answered: (1) many Christian dogmas are, in fact, obscure and far from self-evidently true; (2) Christian preaching held out the threat of eternal punishment quite as much as the promise of eternal happiness, hardly an obvious inducement to conversion; and (3) Jews and pagans alike embraced Christianity chiefly because they perceived evident external signs of its truth, not merely its inner ethical appeal. Against the supposed extrinsic causes: (1) if the political unity of the Empire aided the spread of Christianity in one respect, it equally supplied the imperial machinery of persecution that worked, just as systematically, against it; (2) Platonism and Stoicism were themselves widely held philosophies under emperors such as Antoninus Pius and Marcus Aurelius, and did nothing comparable to displace paganism; and (3) when the barbarian nations eventually invaded the Empire, they found Christianity already firmly established, and adopted the Christian Faith, as Jews, Romans, and Greeks had done before them, because they too were persuaded by its motives of credibility — miracles, the sublimity of Christian doctrine, the extraordinary sanctity and influence of the Church, and the heroic constancy of her martyrs under persecution (cf. Cardinal Newman, A Grammar of Assent).