The ancient triumph of Christianity proved to be the single greatest cultural transformation our world has ever seen.  Without it the entire history of Late Antiquity would not have happened as it did.  We would never have had the Middle Ages, the Reformation, the Renaissance, or modernity as we know it.   There could never have been a Matthew Arnold.   Or of any of the Victorian poets.  Or of any of the other authors of our canon: no Milton, no Shakespeare, no Chaucer.  We would have had none of our revered artists: Michelangelo, Leonardo, or Rembrandt.  And none of our brilliant composers: Mozart, Handel, or Bach.  To be sure, we would have had other Miltons, Michelanglos, and Mozarts in their place, and it is impossible to know whether these would have been better or worse.  But they would have been incalculably different.

By conquering the Roman world, and then the entire West, Christianity not only gave rise to a vast and awe-inspiring set of cultural artifacts, it also changed the way people look at the world and choose to live in it.  Modern sensitivities, values, and ethics have all been radically affected by the Christian tradition.   This is true for almost all who live in the West, whether they claim allegiance to Christianity, to some other religious tradition, or to none at all.   Before the triumph of Christianity, the Roman Empire was phenomenally diverse, but its inhabitants shared a number of cultural and ethical assumptions.   If one word could encapsulate the common social, political, and personal ethic of the time, it would be “dominance.”

In a culture of dominance, those with power are expected to assert their will over those who are weaker.  Rulers are to dominate their subjects, patrons their clients, masters their slaves, men their women.   This ideology was not merely a cynical grab for power or a conscious mode of oppression.  It was the common-sense, millennia-old view that virtually everyone accepted and shared, including the weak and marginalized.

This ideology affected both social relations and governmental policy.  It made slavery a virtually unquestioned institution promoting the good of society; it made the male head of the household a sovereign despot over all those under him; it made wars of conquest, and the slaughter they entailed, natural and sensible for the well-being of the (valued part of the) human race.

With such an ideology one would not expect to find governmental welfare programs to assist weaker members of society: the poor, homeless, hungry, or oppressed.  One would not expect to find hospitals to assist the sick, injured, or dying.  One would not expect to find private institutions of charity designed to help those in need.

The Roman world did not have such things.  Christians, however, advocated a different ideology.   Leaders of the Christian church preached and urged an ethic of love and service.  One person was not more important than another.  All were on the same footing before God:  the master was no more significant than the slave, the patron than the client, the husband than the wife, the powerful than the weak, or the robust than the diseased.  Whether those Christian ideals worked themselves out in practice is another question.  Christians sometimes – indeed, many times — spectacularly failed to match their pious sentiments with concrete actions, or, even more, acted in ways contrary to their stated ideals.  But the ideals were nonetheless ensconced in their tradition – widely and publicly proclaimed by the leaders of the movement — in ways not extensively found elsewhere in Roman society.

As Christians came to occupy position of power, these ideals made their way into people’s social lives, into private institutions meant to encapsulate them, and into governmental policy.   The very idea that society should serve the poor, the sick, and the marginalized became a distinctively Christian concern.   Without the conquest of Christianity, we may well never have had institutionalized welfare for the poor or organized health care for the sick.  Billions of people may never have embraced the idea that society should serve the marginalized or be concerned with the wellbeing of the needy, values that most of us in the West have simply assumed are “human” values.

This is not to say that Judaism, the religion from which Christianity emerged, was any less concerned with the obligations to “love your neighbor as yourself” and “do unto others as you would have them do unto you.”  But neither Judaism nor, needless to say, any of the other great religions of the world, took over the Empire and became the dominant religion of the West.  It was Christianity that became dominant, and once dominant, it advocated an ideology not of dominance but of love and service.  This affected the history of the West in ways that simply cannot be calculated.

Explaining the Triumph of Christianity

But there was no reason this cultural shift had to happen, no historical necessity that Christianity would, in effect, destroy the pagan religions of the Roman Empire and establish itself as the supreme religion and ascendant political and cultural power of its world.  That is why the question I address in this book is so important.  Why did this new faith take over the Roman world, leading to the Christianization of the West? It is obviously not a matter of purely antiquarian interest, relevant only to academic historians.  What question could be more important for anyone interested in history, culture, or society?

To be more specific: how did a small handful of the followers of Jesus come to convert an unwilling Empire?   According to the New Testament, some days after Jesus’ crucifixion, eleven of his male followers and several women came to believe he had been raised from the dead.  Before four centuries had passed, these twenty or so lower-class, illiterate Jews from rural Galilee had become a church of some thirty million.  How does a religion gain thirty million adherents in three hundred years?

As I give lectures around the country on a variety of topics related to early Christianity, this is the question I hear more than any other.   The answers people suggest are wide-ranging.  Many committed Christians appeal directly to divine providence.  God did it.  God guided history so the world would become Christian.  I respect those who have this opinion, but I have one very big problem with it.  If God wanted the world to become Christian, why hasn’t the world become Christian?  If God wanted the masses to convert, why are most of the masses still not converted?   Moreover, just in historical terms, if God made the Roman Empire Christian, why did it take so long?  And why was the job never completed?   Why did non-Christian religions continue to exist at all?  Why are they still in the majority today?

By far the most common secular answer I hear is that the Roman Empire became Christian because the Emperor Constantine converted to the faith.   Constantine was the sole-ruler of the empire in the first part of the fourth century.  Early in his reign he turned from traditional “pagan” religions to become a follower of Christ.  After that, masses of people began to convert, as Christianity went from being a persecuted minority to being the religion of most-favored-status, and eventually the religion of Rome.   So it was all about Constantine, right?

Until recently that is what I myself thought.  But I no longer think so.  On the contrary, I think Christianity may well have succeeded even if Constantine had not converted.   That will be one of the theses of this book.

Still, it cannot be disputed that after Constantine’s conversion, masses of people came to embrace the Christian faith.  Not absolutely everyone.  And not immediately after Constantine did so.  Indeed, not even a century after Constantine’s death.  But eventually Christianity became the religion of the multitudes, and the Roman pagan religions they had formerly practiced more or less disappeared or, in a few instances, went underground.  For those supporting the Christian cause, this has always been considered a real triumph.

I will not, however, be writing this book in a triumphalist vein.  That is to say, I will not be celebrating the rise and eventual domination of Christianity, claiming it was inherently superior or even necessarily a very good thing.  On the other hand, I do not want to claim it was bad either.  Ultimately good or ultimately bad:  as a historian I will remain neutral on these kinds of value judgments.  In part that is because the triumph of Christianity also entailed losses, especially for the devoted followers of other religious practices.  Whenever one group wins a struggle, others lose.  Those of us with historical interests need to consider both winners and losers.