Today sees the last in the series of Westminster Faith Debates, which have been going on since February at the Royal United Services Institute in Whitehall. Organised by Lancaster University and the think-tank Theos and chaired by Charles Clarke, the former cabinet minister, the sessions have explored various aspects of the intersection of religion and politics, from the place of religious education in schools to the highly controversial role of faith-based initiatives in plugging the increasingly obvious holes in the welfare system.

The debates have brought together social scientists with politicians, media pundits and religious leaders.  Speakers have included Trevor Phillips, Richard Dawkins, Rabbi Julia Neuberger and the New Statesman's own Mehdi Hasan.  Elizabeth Hunter, the director of Theos, told me that for her the best element of the series has been the breadth of the audience.  "We've filled the room with committed, interested people of all faiths and no faith," she says.  "It's been unusually diverse and engaged, which has meant the Q and As have been lively and often challenging."

Hunter singled out last month's debate on religious freedom, which featured  Michael Nazir Ali, the former Bishop of Rochester, and Lisa Appignanesi among others, as her own personal highlight:  "We had a real range of opinions on the panel, and indeed in the audience, but the discussion was serious, not consensual, but civil. So many people said to be afterwards that it was the best thing they've seen on the subject. Most of the public conversation about religious freedom and equality descends into tribal mudslinging and this was very different."

The debates were certainly well-timed.  The first four months of the year have witnessed an extraordinary cranking-up of tension, at least in terms of the public debate around religion and society.  The tone was set during that remarkable week in February when Baroness Warsi went to the Vatican to warn the Pope about militant secularism while Richard Dawkins, highlighting research that suggested declining religious literacy even among professed believers, memorably fluffed a challenge from Dr Giles Fraser to recall the full title of The Origin of Species. 

This past week has seen more of the same, with the British Humanist Association extending its campaign against faith schools and Catholic educators under fire for (as they see it) defending the traditional understanding of marriage.  In between we've had rows about proposed "gay cure" bus adverts, the legality of council prayers  and the future of the bishops in a reformed House of Lords.

Why is all this happening now? It's common to date the current, fevered debate on the place of faith in modern Britain to the fallout from 9/11 or, beyond that, to the Rushdie affair of the late 1980s.  But both those traumatic events are beginning to recede into history.  Both "offence" and terrorism remain big, unresolved issues but the focus today is less dramatic and more fundamental: it's about how to maintain a cohesive society with increasingly few shared beliefs and assumptions.

The first Westminster debate, back in February, raised the issue of "superdiversity" which goes to the heart of the issue.  Under the principle of "diversity", which forms the basis of much recent legislation (notably the 2010 Equality Act) people claim rights as members of communities, whether defined by reference to their ethnicity, their sexuality, their physical capacity or their religious adherence. 

This makes things nice and simple for lawmakers and the courts, even if it gives endless scope for litigation and encourages something of a grievance culture.  But it's a blunt instrument, and outdated even as the ink was drying on the last piece of legislation.  People have multiple identities, which change through life and may find themselves in tension even within the same individual.  Religion is one way in which people define themselves.  For some it is of supreme importance, for others it's peripheral, or others still it is (as the Facebook status offers) "complicated."  One size does not fit all.  Everyone is, to some extent, their own "community".

In her presentation tonight on the subject of current trends, Professor Linda Woodhead of Lancaster University (who has been leading the debates) will argue that what we call religion has changed dramatically in recent years.  Whereas it was once bound up with local and national community it has become something individual and individually chosen.  It's no longer "a matter of belonging to a clerically-led community, affirming unchanging dogma and holding conservative social attitudes".  Claims by "male leaders to represent religious communities are more tenuous than before."  It's all about "associating with like-minded people through real or virtual networks". 

Yet if religious diversity is just another manifestation of modern capitalist consumerism, as such a view would imply, why does it remain so politically, and personally, charged?  And take the ultimate hierarchical, clerically-led and dogma-affirming religious institution, the Roman Catholic Church.  Under pressure it might be, but it is precisely those features that Woodhead singles out as problematic that self-identifying (rather than merely cultural) Catholics find most attractive and that are growing.  There has recently been a small increase in the number of women training to be nuns, for example, and younger nuns are more likely to join traditional, habit-wearing convents than the more liberal orders whose American leaders have recently annoyed the Vatican.

What I would want to say, contrary to Woodhead's rather optimistic conclusions, is that religion has very little to do with personal spirituality, although it has traditionally been the main vehicle through which personal spirituality is expressed.  Far more central, historically, has been its role as a mechanism of group cohesion, as a social glue and as a source of communal morality.  That's why it has always been closely involved with politics, and perhaps why the decline of formal religious observance has coincided with a similar decline in membership of political parties, voting and faith in the political process as a whole. 

In religion as in politics, what is left when most ordinary people get bored is a hard core of committed and slightly obsessive activists -- moderates as well as extremists, by the way, scoffers as well as true believers.  When the enthusiasts on all sides no longer represent a social consensus or a mass activity, the debates get more, not less, heated.

Nevertheless, as Hunter says, religion still is and will continue to be central to many people's lives. "If we don't engage and understand it, if we're not willing to really listen and have serious conversations about how we live together well then we're all in trouble."  Recent months have demonstrated that beyond all doubt.