We have a government that likes to "do God". To be more accurate, we have a government including some members who like to talk publicly about the importance of religion in general, and of Christianity in particular. Few are keener to talk about it than Eric Pickles. Writing in the Telegraph last week the larger-than-life Communities Secretary was characteristically effusive about the contribution that Christianity made to British public life.

It "has shaped the heritage, morality and public life of Britain; and... continues to influence our society for the better," he wrote. He further contrasted the positive story of the country's "Christian ethos" (including the Reformation, which was "entwined with British political liberty and freedoms" - a message unlikely to go down well with Roman Catholics) with the danger posed by secularism, as represented by "the intolerant National Secular Society".

This intervention is just the latest in a long line of ministerial (and prime ministerial) pronouncements since this government came to power. To take a few examples, David Cameron said in a speech last year celebrating the 400th anniversary of the King James Bible that "we are a Christian country and we should not be afraid to say so." Baroness Sayeeda Warsi - whose new title, since the reshuffle, is "senior minister of state and minister for faith and communities" - wrote in the Telegraph earlier this year warning that "a militant secularisation is taking hold of our societies", a "deeply intolerant" creed that "demonstrates similar traits to totalitarian regimes."  Michael Gove arranged for copies of the King James Bible to be distributed to schools.

Such statements and gestures may reflect an actual policy agenda, such as the government's continued encouragement of faith schools. Making pro-faith noises is also a way of appealing to a group of core supporters (Britain's small but politically active "religious right") and of differentiating the Conservatives from the Liberal Democrats, who are led by a self-proclaimed atheist. It may just be empty rhetoric. Pickles was especially keen to reassure Christian activists that the government is on their side despite such things as same-sex marriage or the spectacle last week of British government lawyers at the European Court of Human Rights arguing that a Christian woman had no right to wear a cross at work.

That one poses a particular problem for Pickles, given that both he and David Cameron have previously denounced such restrictions and even promised to enshrine the right to wear crosses in new legislation. In his latest article, Pickles proclaimed that "banning discreet religious symbols for reasons of political correctness is not acceptable" before going on to justify the government's legal position, bizarrely, as "resisting Brussels interference and gold-plating of what should be a matter for common sense."  

It's interesting that cross-wearing has recently become a touchstone issue. Whatever the legal arguments, the cases reflect a sense among some that Christianity is ceasing to be taken for granted in British society but has become a particular identity that needs to be asserted. Many Christians certainly feel themselves to have been "marginalised". A survey carried out for Premier Christian Radio a few years ago found that almost three quarters believed this to be the case. The marginalisation "narrative", in which the high-profile court cases play an important part, has been pushed by campaign groups such as Christian Concern (with support from parts of the media, especially the Mail and the Telegraph). Prominent Christian leaders reinforce it, too: most notably Scotland's Cardinal Keith O'Brien, the Archbishop of York John Sentamu and two retired Anglican prelates, Michael Nazir-Ali and George Carey.

According to this narrative, a small cadre of secularists, acting in the name of multiculturalism and/or equality, are aggressively relegating Christianity from the centre of public life, where it has been for centuries, to the periphery. Conversely, secularists and some liberal Christians argue that what the campaigners are actually lamenting is the loss of the power and privilege that the churches used to enjoy. I find both claims implausible. There is clearly nothing marginal about a religion whose representatives sit by right in the nation's legislature, which runs a third of the country's state schools and to which half the population, on the most recent figures, still claims to belong. But at the same time Christianity is clearly not as strong as it was. By any standards, decline in religious observance has been one of the most striking features of the past fifty years.

While the decline in actual attendance at church services now seems to be slowing, the proportion of the population that claims a religious affiliation has fallen dramatically in the past two decades, especially among younger people. The result is a sharpening of the boundary between believers and the rest of society - especially since a higher proportion of church members now identify themselves as evangelical or otherwise theologically conservative.

In the past, the fact that the majority of the population paid lip-service to the idea of a Christian nation meant that the true believers, always a fairly small proportion of the whole, felt themeselves to represent the moral core of society. Traditional "Christian" attitudes were widely shared even by people who rarely if ever went to church. Today, they are far from universally adhered to even by Christians.

It's no coincidence that the one issue above all that excites many believers in the marginalisation narrative is the government's stated intention to open marriage to same sex couples. It's not simply a question of prejudice or bigotry, as some (including apparently Nick Clegg's speechwriters) appear to believe. It's more that the issue reveals the gulf that separates some traditionalists from what has become the moral centre of gravity in wider society. The battle today is within the churches, not between Christians and secularists. Opponents of the change thus feel in danger of being doubly marginalised, fighting liberals in their own ranks. "Aggressive secularists" make a convenient scapegoat.

In his latest contribution, Eric Pickles promised to take note of opponents' "legitimate fears" that churches might be forced by the European Court of Human Rights to marry gay couples. Whether or not such fears are actually legitimate (it seems unlikely) his reassurance is unlikely to cut much ice. The real issue is the government's proposal to allow any same sex couple, religious or otherwise, to get married. Ironically, special exemptions and opt-outs written into law would only underline the new status of Christians as a "marginalised" minority interest group instead of one that has, in Pickles' words, "a unique position in British society and a particularly strong claim to be heard."