The secularisation thesis has long dominated the study of religion in Britain, presenting a powerful set of arguments about the impact of various processes of modernisation – including industrialisation, urbanisation, advances in science and technology and rapid social changes – on religion and religious institutions since the late eighteenth and early nineteenth centuries. In more recent decades, revisionist scholarship, led by sociologists and historians, has challenged central aspects of the secularisation thesis, but still its grip remains firm. Drawing on decades of his research and writing, Steve Bruce offers a concise defence of the theory in British gods, identifying himself as the main spokesperson for what he claims is now a frequently caricatured and derided thesis. The book aims to refute recent criticisms and counter-arguments to British secularisation through an examination of several localised case studies and themes. Bruce outlines various arguments about the extent, nature and causes of the weakening of religious interest and participation since the mid-nineteenth century, with a particular focus on the twentieth century as a period of accelerated decline. Ultimately, Bruce concludes that secularisation is now irreversible – not only is there an absence of shared religious knowledge in twenty-first century Britain, but religion is generally seen as a negative influence on people and society, and the number of people who are avowedly religious has dipped below a level where a religious revival is probable. Bruce suggests that religious and spiritual people are now so numerically insignificant, at less than 10 per cent of the population, that they have little chance of influencing the non-religious majority, who are becoming ever-increasingly hostile to religion.

British gods describes and explains the various factors that led British religion to lose its power, popularity and plausibility. The book begins by exploring the decline of elite patronage of local parishes of the state Church which, Bruce argues, reinforced the trend towards British people regarding religion as a matter of personal preference and removed the social stigma of choosing not to be religious. It concludes by examining the changing relationship between religion and politics. Bruce suggests that, while twentieth-century Christianity benefited from the inertia of British governments in being afforded a degree of respect that reflected the Churches’ nineteenth-century popularity, since the Second World War, laws and norms have increasingly been brought into accordance with general religious indifference, and privileges and exemptions for faith groups are no longer seen as politically important.

Early sections of the book seek to investigate and interpret the ways in which various elements of modernisation do not evenly or equally affect all sections or regions of society. Chapter ii examines a handful of local case studies, including three Scottish islands and four Welsh rural parishes, to demonstrate the dependence of secularisation on localised conditions. Bruce finds that, within communities, a shared religious culture is sustained by passing on traditional attachments and pressuring people on the fringes of organised religion to maintain an active involvement. Therefore, where there is strong internal cohesion and relative isolation from the changing culture of the outside world, communities maintain their religiosity, but where these conditions are eroded, religion is weakened. Chapters iii and iv then explore the ways in which the Churches have responded to their demise. Bruce explains why the clergy continue to play important social roles despite the unpopularity of the faith they represent. He concludes that British people now accept the secular functions that clergy play in local and national life precisely because the Churches no longer have any real political or social power, as they once did. Bruce also asserts that, while the power and popularity of Christianity historically allowed the Churches to split into competing fragments, now that religion has declined, the Churches have responded by merging and reuniting with each other. Bruce contends that this phenomenon reflects the Churches’ impotence; it is due to a lack of interest and understanding, both inside and outside the Churches, that once competing groups have been forced to overlook those issues of dispute that once divided different denominations of Christianity.

Perhaps the main thrust of British gods is Bruce's efforts to refute arguments that British religion has not so much declined as changed its form. The book addresses various counter-trends to secularisation, such as the post-war growth of the charismatic Christian movement, the effects of immigration on British religion, including the growth of migrant Christians, such as West Indian and West African Pentecostalists and Irish Catholics, and the growth of non-Christian faiths, such as Islam. It also investigates the contemporary status of folk religion and superstition, as well as spiritualism and spirituality. But Bruce concludes that none of these developments represent net growth in British religion; rather, they are mere reflections of the many symptoms of secularisation and religion's ever-shrinking status and numerical strength. Migration from traditionally religious countries has offset only a fraction of the decline in Christianity, and interest or participation in religion and spirituality is confined to ever smaller and culturally isolated parts of the population.

As Bruce admits, what is disputed about the secularisation thesis is not its assertion of the basic fact of religious decline in Britain. Most people accept this. Rather, what is divisive about the theory is its explanations of how and why this happened. While the quantifiable data used throughout British gods – on religious attendance, membership and the use of ceremonies to sanctify rites of passage – can provide a good general indication of religious health, such statistics do not provide evidence of causal explanations. Bruce makes clear his dislike for the myriad of criticisms that have been advanced by post-modernists and other relativists, but this makes his uses of qualitative data – from historical reports, newspaper articles, local histories, everyday social interactions – deeply problematic. As with nineteenth-century commentaries on religious decline, qualitative accounts tell us much more about what contemporaries perceived to be happening and why they thought it was happening, rather than providing us with evidence that their perceptions were right. British gods provides a lively addition to the scholarship, but its attempts to explain British secularisation will likely prove contentious.