Throughout much of the twentieth century, a dominant strand of sociological theory held that modernisation — industrialisation, urbanisation, rising education, the spread of science — would inevitably erode religion's social and personal significance, a prediction known as the secularisation thesis. Western Europe, in many respects, has followed something close to that trajectory. Large parts of the rest of the world, including some of the most economically developed and technologically modern societies on earth, have not, which has forced sociologists to substantially rethink what the original theory got wrong.
Where the thesis fits, and fits well
In much of Western Europe, church attendance, religious identification, and the social authority of religious institutions have declined markedly alongside industrialisation and rising material prosperity over the past century, a pattern the secularisation thesis predicted reasonably well. Early sociologists like Max Weber and, later, Peter Berger built substantial theoretical frameworks around this observed trend, generally arguing that rationalisation, scientific explanation, and institutional differentiation (religion losing its former grip over politics, education, and law as distinct specialised institutions) would steadily push religious belief and practice toward the margins of public and even private life, treating this as close to a universal feature of modernisation itself rather than a pattern specific to one region's particular history.
Why the United States broke the pattern early, and why the theory's global reach broke later
The United States presented an early and persistent complication: a highly modernised, industrialised, wealthy society that nonetheless retained comparatively high levels of religious belief and practice throughout the twentieth century, a pattern that never fit the secularisation thesis's predicted trajectory cleanly. As sociological research expanded its focus beyond Western Europe, the pattern grew starker still — many rapidly modernising and industrialising societies across Latin America, Africa, and parts of Asia have seen religious practice remain strong or even intensify alongside economic development, rather than decline as classical secularisation theory predicted. This global evidence prompted a substantial rethinking within sociology, with scholars like Berger himself later revising his earlier secularisation arguments and proposing alternative theories — including that religious pluralism and competition, rather than modernisation itself, may better explain the patterns actually observed.
What we're still unsure about
That religious practice has declined significantly across much of Western Europe alongside modernisation, while remaining strong or growing in many other modernised or modernising societies, is well documented empirically. What remains genuinely unsettled is why — whether the classical secularisation thesis was simply wrong about a universal mechanism, whether it describes a real but regionally specific pattern tied to particular European historical circumstances, or whether some more refined version of the theory (focused on institutional differentiation rather than personal belief, for instance) still holds up better than the discredited simple version — is an active, unresolved debate within the sociology of religion.
This sits inside Religious Institutions & Secularisation, one of seven topics in Institutions, one of four domains in Sociology, one of seventeen subjects the app can quiz you on.