“Non-religion”, however, can be understood in a broader sense as meaning atheism, agnosticism, non-religious secularism, or simply religious indifference – as well as other outlooks that are harder to classify and record.

Understood this way, the number of non-religious people extends into the hundreds of millions in Europe alone. Yet in spite of this, non-religion had attracted little serious study by social scientists before the turn of this century, and it remains of marginal interest in many quarters. This is partly because non-religion has been another casualty of the dominating Enlightenment view of modernity – which sees modernization as involving the steady rationalisation of peoples and thought, causing, in turn, religion to decline.

This view of modernity has been widely challenged since it emerged, often in critiques which defend religion as having an important role in modern society. Amongst other things, these critics contend that religion is less vulnerable than we had anticipated it would be, and that it is potentially more rational than we thought. Interestingly, this becomes a debate purely about religion itself – it reinforces the idea that religion is the sole issue at stake and remains a singular oddity that needs to be explained.

A small, but growing number of non-religion scholars take a different view: We argue that the study of religion does not have to be about religion alone. This sounds like a contradiction in terms, of course, but actually it reflects how far language has become strait-jacketed by the idea that religion is a unique phenomenon. We are so accustomed to the idea that religion is singular and without alternative, that we have yet to developed a more generalised term for the collected perspectives of religion, spiritualism and non-religion –as, for example, we use the term “gender” to include men, women, intersex and transgendered positions.

This is not just an academic issue or one of quibbling about categories. The tradition of treating non-religion as a non-entity means that we gloss over some significant social issues that diverse and pluralist societies should be addressing.

One example is the dialogue between faith and non-faith groups. Taking the idea of non-religion seriously involves taking seriously the idea that religious and non-religious communities co-exist and are likely to co-exist indefinitely. The way these groups interact has, in a globally communicative world, become important in national and international politics, civil society and personal relationships. They can either treat one another with tolerance and understanding, or with fear and misunderstanding. A non-religious position is never, however, a position of neutrality.

The idea that religion is something, and non-religion is nothing, can have different practical implications. It is, on the one hand, related to the idea that religion is strange and problematic whereas non-religion is normal and benign. On the other hand, the same stance can also lead to the view that religion is diverse, rich, communitarian, meaningful and therefore positive; while non-religion lacks the same capacity to enrich human life. Thus, by separating the two on this basis, we give both sides a legitimate cause for grievance and impair attempts to facilitate more positive relationships between them.

Given the lack of research and discussion about non-religion, there are important and urgent questions to be asked about it. For example, cognitive anthropologists and psychologists studying the cognitive conditions for theism have begun to notice that their work is incomplete unless they also understand the cognitive conditions of non-theism. In social anthropology and sociology, researchers have begun to explore the role of symbolism and communal aspects of non-religious life, helping us to understand more about contemporary human societies and challenging the view that symbolism and ceremony have a special relationship with religion.

For students of politics and international relations, questions relate to the relationship between non-religious perspectives and political secularism, liberalism and democracy – the same questions, in fact, that are currently being asked of religion. And in religious studies in general, establishing what constitutes non-religion is helping to answer fundamental questions about the nature of religion itself.

All of this is of practical significance. Answering such questions will impact upon people’s understandings of themselves and others. Given the importance of inter-cultural and intra-cultural dialogue in diverse, pluralist societies, the existence of a large, silent majority – as the non-religious are, especially in Europe – is a problem. Initial findings from my own research, for example, indicate that different non-religious groups perceive religiosity in different ways. This and work like it, which recognises non-religions as participants in “religious”conversations, is necessary to facilitate real and productive dialogue.

Lois Lee is founding director of the Non-religion and Secularity Research Network, a doctoral candidate at the University of Cambridge, and was a Junior Visiting Fellow at the IWM Institute for Human Sciences in 2010. She is an editor of the new journal Secularism and Nonreligion. More information about non-religion research can be found at www.nsrn.co.uk.