Just six years after Constantine the Great bowed his knee to the God of the Christians, he enlisted the church’s leadership to serve the Roman empire. In AD 318, bishops were still reeling from the vicious Diocletian persecution, with fresh memories of the torture and execution of their fellow believers. Under a new law, they now gained the power to rule on legal disputes, with their judgments backed by imperial authority and unappealable to civil tribunals. It was a breathtaking reversal of fortune.

Initially, this new judicial role for bishops – the audientia episcopalis – amounted to little more than legally binding arbitration: a voluntary alternative to the empire’s overburdened and corrupt courts. (Later it would evolve into a fully developed ecclesiastical legal system.) Even at the time, though, Constantine’s law marked a first step in the Christianization of state and society, a development that would have far-reaching consequences.

The process of Christianization that Constantine’s law inaugurated wasn’t a wholesale theocratic revolution such as in Iran in 1979. Rather, it advanced fitfully and inconsistently over generations. Beliefs rooted in the New Testament – the sanctity of human life, the rights of the poor, monogamy, the equality of each human being before God – slowly reshaped law and custom. For example, in the two centuries after Constantine, his successors gradually restricted infanticide, gladiatorial games, abortion, forced prostitution, and sexual abduction. They limited the tyranny of creditors over debtors, eased the process for manumission (without abolishing slavery itself), and established organized charity for the poor and a right to asylum in churches. Eventually, Christian legislators introduced the novel idea of consent by both parties in marriage.

Changes in law reflected and spurred on changes in culture. As Christianity spread, the gospel of a crucified God effected a slow-moving yet utterly radical transformation in worldview: Jesus promised that the meek, not the mighty, were the blessed who would inherit the earth. From this transformation, the historian Tom Holland argues in his 2019 book Dominion, would eventually spring the modern ideals of emancipation, human rights, and democracy. As a result of the process Constantine began, according to Holland, today Christianity remains – admittedly in a somewhat disguised form – the operating system of the West.

For how long? Today, the process of Christianization launched by Constantine has gone into reverse, at least in the West. According to social scientists, secularization continues apace, as each new generation reports lower rates of belief, religious affiliation, and church attendance than the last. By some accounts, in the United States secularizing trends seem to have slowed in recent years, and some Catholic, Orthodox, and Pentecostal churches in North America and Europe even report upticks in adult baptisms and Sunday attendance, especially by young men. Awakenings on US college campuses have undoubtedly changed individual lives.

Yet as the demographer Ryan Burge reports in his new book The Vanishing Church, statistically these conversions, however heartening, don’t balance out the overall slide in religious belief and practice. As older, more religious cohorts are replaced by younger, less religious ones, Christians appear set to become a minority in the United States just as they have in other countries historically identified with Christendom.

Anna Dillon, The Avenue at Avebury, oil on board, 1996. Used by permission.

As Christianity has declined demographically over the past fifty years in Western countries, its influence in state and society has declined as well. The spread of support for euthanasia and easy abortion access testifies to the loss of an earlier Christian consensus on the sanctity of human life. Declining marriage rates and the legalization of same-sex unions reflect the collapse of traditional Christian norms in the wake of the sexual revolution. Even falling fertility rates – to below-replacement levels in much of Europe – appear to correlate with growing secularization.

The clearest symptom of de-Christianization, however, has less to do with any given ethical issue than with something more fundamental. Christianity teaches that each human being is made in the image of God, and that humankind, in all its diversity, is one whole. The theological doctrine of equality before God, as Holland reminds us, undergirds any modern appeals to equality under the laws or to intrinsic human rights. And the biblical insistence on the unity of the human race relativizes all divisions between ethnic and national groups. Taken together, these insights are the essential underpinning for liberal democracy.

As Christianity recedes, this legacy is giving way to an age of nihilism – that, at least, is the thesis of the sociologist James Davison Hunter’s 2024 book Democracy and Solidarity. According to his diagnosis, the vacuum left by de-Christianization is being filled with the naked will to power, whether left- or right-coded. In contrast to Nietzsche’s version of the will to power, which claimed to be life-affirming, today’s nihilism is marked by what Nietzsche called ressentiment, as mutually hostile groups – Hunter terms them “counter-publics” – define themselves against one another by means of “shared narratives of injury.” The logic of ressentiment pushes people to reject the common search for truth in favor of seeking to crush their group’s adversaries. Ultimately such nihilism is incompatible with commitment to universal human dignity and rights. (While Hunter’s book focuses specifically on the American experiment, parallels in other Western societies seem clear enough.)

Today, as always, our vocation remains the same: to live already now as citizens of the New Jerusalem.

How are Christians to respond to de-Christianization and its aftereffects? One path is to embrace ressentiment and wield Christian identity as a weapon in the nihilistic war of one group against another, at the risk of betraying the very faith one seeks to defend. Prominent figures today have chosen this approach, brandishing Christian words and images in service of anti-Christian ends. Alternatively, Christians might abandon the public sphere and retrench, forming cloistered communities to wait out the “new barbarism,” to borrow a phrase from Rod Dreher’s 2017 book, The Benedict Option.

Christians at the time of Constantine’s conversion faced similar challenges but adopted a different approach. Their ranks were tiny compared even to the secularized present – they made up perhaps 10 percent of the Roman Empire’s population. Like Christians today, they were often internally divided and imperfectly faithful. But despite their demographic insignificance, they possessed a remarkable confidence. As Cardinal Joseph Ratzinger put it (borrowing a phase from Arnold Toynbee), they were a “creative minority,” whose power lay not in numbers but in their spiritual vitality and transformed lives. To quote the third-century bishop Cyprian of Carthage, “We are philosophers not in words, but in deeds.… We do not speak great things, we live them.”

These early believers, understandably grateful as they were that Constantine had embraced the faith and ended persecution, could not have foreseen the centuries-long project of Christianization he would begin: its successes, its abject failures, or what now appears to be its dismantling. Their confidence didn’t depend on their group’s ability to reform the empire’s laws (though they welcomed legislation that reflected the truths of the gospel) or revolutionize their society’s mores (though their example eventually had that effect, even if unevenly). Rather, they were certain of Jesus’ promise that “the gates of hell will not prevail” against his church in the long run, because he was the Lord of history and would one day return to make all things new.

Christians today, if demoralized, can take courage from these forerunners in the faith. Church decline and the de-Christianization of culture and social institutions are painful and, from a Christian perspective, plainly bad for human beings. But, according to our faith, they aren’t the end of the story. Today, as always, our vocation remains the same: to live already now as citizens of the New Jerusalem.

The Nicene Creed reminds us where the future is headed: “He shall come again in glory … whose kingdom shall have no end.” What will come after Christianity? Christ himself. In the interim, he has given his followers, whether few or many, great things to live and work to do.