By Symon Hill

“All have the right to express themselves through their dress.”

It may sound like she's stating the obvious, but Na'ima B Robert’s choice of clothing triggers negative reactions – including from some who see themselves as supporters of equality and freedom. A British Muslim author, she wears a niqab (a Muslim face veil) and leaves only her hands and eyes visible.

“Our society has a responsibility to protect the rights of citizens," says Robert, "as long as they do not impact negatively on the freedoms of others."

But the niqab has provoked controversy in recent years – the British cabinet minister Jack Straw famously asked his constituents to remove it, while the Daily Express called for it to be banned.

This may be the most extreme of the recent assaults on freedom of dress in Britain, but it is far from being the only one. Related controversies to hit the headlines include a Christian employee told not to wear a cross on a necklace, a Muslim hairdresser refused employment for wearing a headscarf and a Sikh school student struggling for her freedom to wear a bangle. These are just three examples of the many that could be mentioned. Not all the groups involved are religious: shopping centres have banned “hoodies”, while a Goth couple in Yorkshire were barred from the local bus service.

In our diverse society, clothes can be an important marker of identity. Robert likens forms of dress to the emblems of a “tribe”, which she loosely defines as a group with shared beliefs or lifestyles. She suggests that not only faith groups, but Goths, Emos, city bankers and “yummy mummies” are tribes, marked out by their style of dress.

Given the importance of clothing to personal expression and religious identity, we might expect to see united campaigns against assaults on freedom of dress. Unfortunately, notions of human rights developed in words-based cultures that placed a high value on free speech while barely considering clothing. This is one reason why the media have tended to focus on each dispute individually, spectacularly failing to see the connections between them. To make matters worse, some campaigns for freedom of dress seem destined to drive away likely sympathisers.

Take, for example, the case of Lydia Playfoot, who took her school to court at the age of 16 after they banned her from wearing a Silver Ring, a symbol used by some conservative Christians to demonstrate a commitment to sexual abstinence before marriage. Here was a young woman wearing something that had deep meaning for her and harmed no-one. It is not necessary to agree with Playfoot's views on religion or sexuality in order to oppose absurdly authoritarian dress codes. She was opposed by the hardliners at the National Secular Society, along with people who hold uniforms in far too high a regard.

Playfoot should therefore have attracted the backing of any advocate of free expression. But her supporters seemed to regard other religious groups not as potential allies but as rivals. They suggested that members of other faiths were enjoying privileges denied to Christians. I approached Christian Concern For Our Nation (CCFON), who were at the forefront of Playfoot’s campaign. CCFON emphasise “religious freedom” as one of their major concerns, but when I asked if they would campaign alongside other faith groups for religious liberty, they refused to answer my questions.

Not all Christians are so hesitant. Simon Latham, a Quaker who wears traditional Quaker dress, insists that “freedom of dress, when freely chosen, is an important expression of culture, religion, personality and identity, and should be protected in law”. I am delighted that Latham and Robert both recognise that freedom of dress is a right not only for their own group but for others. But most campaigns in support of the freedom to wear a cross or a hijab have been waged by members of the religion associated with them. It saddens me to see anyone campaigning only for their own liberty while neglecting that of others.

This is in part a symptom of a society confused about the role of religion. The decline of church influence has thrown some Christian leaders into a defensive panic, in which they cling on to the fantasy of a “Christian country”. But Christendom – the system by which the Church and state condoned and upheld each other – was a power arrangement that had little to do with Christianity’s revolutionary origins. Discussions of Christians’ liberty have become entangled in this confusion, while debates around Muslims’ liberty are immediately enmeshed in the tangle of fear and prejudice surrounding Islam.

The most obvious example of such prejudice is the assumption that the hijab and niqab are oppressive. When people are coerced into wearing them, this is certainly oppressive – but it is the element of compulsion, not the clothing itself, that makes this an act of oppression. Secular extremists who say “you must not wear this” want to deny freedom as much as any religious bigot saying “you must wear this”. As we have seen in France, the secular imposition of uniformity does not create equality and respect; it fuels hostility and resentment.

Religious liberty is truly possible only if no one religion or worldview is allowed a dominant influence in society or political structures – whether it is Christianity, Islam, secularism or anything else. The post-Christendom situation we now face is an opportunity to promote authentic liberty for both the religious and the non-religious. At its best, religious liberty can encourage groups to work together when they find common values and to debate their disagreements with respect.

Such respect cannot of course be enforced simply by legislation; tackling prejudice is more complicated. Two important points need to be recognised before we can achieve significant change, whether legal or cultural. First, we need to see freedom of dress as an essential aspect of free expression. Second, we must admit that we will not achieve freedom of dress – or other liberties – if Christians campaign only for Christian freedom, Muslims for Muslim freedom and so on. Campaigning effectively for freedom means supporting other people’s freedom.

Symon Hill is a writer, trainer and activist, and is co-director of Ekklesia. He writes regularly for the Guardian, and his first book, The No-Nonsense Guide to Religion, will be published in March 2010.