How the West Became Secular: A Brief History of a Very Recent Idea

It can feel, in much of the contemporary West, as though secularism — the assumption that public life, knowledge, and morality can and should proceed without reference to God — is simply the default, neutral backdrop against which all other beliefs are the exceptions requiring explanation. Historically, this is almost exactly backwards. Secularism as a dominant cultural assumption is a remarkably recent development, and understanding how it emerged tells you a great deal about what it actually is.

A Very Long Christian Default

For most of the last seventeen centuries, the default assumption in the West was some form of Christian belief, dating roughly from Constantine's legalization of Christianity in the early 300s through at least the eighteenth century. This didn't mean everyone was a devout believer — plenty of nominal, cultural, and even skeptical Christianity existed throughout this period. But the basic framework for discussing truth, morality, meaning, and the nature of reality assumed, almost without needing to argue for it, that God existed and that Christian revelation was at minimum a serious candidate for describing reality accurately.

The Enlightenment's Opening

That framework began to crack, gradually and unevenly, during the period historians call the Enlightenment, roughly the late 1600s through the 1700s. Philosophers like John Locke, Voltaire, and David Hume began developing accounts of knowledge, ethics, and political authority that, while many of these thinkers remained personally religious in some form, increasingly did not require appeal to divine revelation to get off the ground. Reason, empirical observation, and natural law became the preferred starting points for serious intellectual work, gradually displacing appeals to Scripture or church authority as the default currency of public argument, at least among the educated classes.

This was not, in its earliest stages, a wholesale rejection of Christianity so much as an attempt to find common intellectual ground that could function across an increasingly religiously diverse and argumentative Europe, still reeling from the era's wars of religion. But the tools developed for that purpose proved, over time, capable of operating entirely independently of the religious assumptions that had first motivated their creation.

Nietzsche and the Recognition of the Stakes

By the nineteenth century, a smaller number of thinkers began recognizing more starkly what was actually at stake in this gradual shift. Friedrich Nietzsche's famous declaration that "God is dead" was not, as it is sometimes popularly misread, a triumphant celebration — it was closer to a warning. Nietzsche understood that Western moral and cultural life had been built on Christian theological foundations for so long that few people had reckoned with what would remain once those foundations were genuinely removed rather than merely questioned. His own answer was unsettling even to many secular readers: without God, he argued, the West's inherited moral commitments — human dignity, equality, compassion for the weak — had no remaining logical foundation at all, and would eventually have to be either abandoned or replaced with something else entirely.

The Twentieth Century's Acceleration

The twentieth century saw secularization accelerate dramatically across much of the West, driven by a combination of factors: two world wars that shook confidence in providential narratives of Western Christian civilization, rapid scientific and technological advance that seemed, to many, to shrink the explanatory space available for religious answers, and the steady privatization of religious belief as something increasingly treated as a personal preference rather than a shared public framework for understanding reality. By the century's end, in much of Western Europe especially, active religious practice had declined to levels that would have been unimaginable to observers even a hundred years earlier.

A Worldview, Not a Neutral Absence

What this history reveals is that secularism is not simply the absence of belief that remains once religious claims are subtracted — it is itself a substantive set of commitments about meaning, morality, and human purpose that developed along a specific, traceable historical path, replacing an equally substantive set of Christian commitments that had held cultural default status for far longer. Recognizing that history is the necessary starting point for any honest comparison between the Christian creeds this network explores and the implicit "creed" of contemporary secular culture: not a conversation between one worldview and neutral no-worldview-at-all, but between two competing accounts of reality, each with its own history, its own assumptions, and its own case to make.

Compare the alternative this history displaced: the world Constantine inherited and the faith that shaped the West for centuries.