What is still puzzling about the debate over Christian unions in some colleges and universities being refused recognition by student unions is the underlying assumption that seems to be at work. It's as if these student unions are saying that disagreement itself is disturbing - that having different convictions is so violently disruptive that no open exchange can be allowed. To avoid conflict and offence, there must be no possibility of certain views surfacing in the public sphere.

What this does is focus our minds on the whole - sensitive - question of "offence". Are there views whose expression is automatically so hurtful to some that they have to be restricted for the sake of general good order and justice? Well, we legislate on that basis, certainly, where racism or holocaust denial or similar matters are concerned. Talking in a way that denies the human dignity of others - by racist abuse, by labelling Jewish survivors of the Shoah as liars - is outlawed. Such ideas are unjust: they place people at a disadvantage and deny due respect. And we quite rightly regard language abusing or dehumanising homosexual people in the same light: the language of contempt and disgust is not admissible. We recognise the reality and the atrocity of hate crimes in this context as in others, and we recognise that hateful speech is close enough to hateful action for it to deserve sanctions against it. But beyond this, we sometimes seem to be unclear.

Quite often in discussion of Christian attitudes to homosexuality (and this is often the presenting issue where Christian unions are concerned), it is taken for granted that any statement that a form of behaviour might be sinful is on a par with the expression of hate, so that it is impossible for a conservative Christian, Catholic or Protestant or, for that matter, an orthodox Muslim to state the traditional position of their faith without being accused of something akin to holocaust denial or racial bigotry. Yet the truth surely is that while it is wholly indefensible to deny respect to a person as such, any person's choices are bound to be open to challenge. Any kind of behaviour or policy freely opted for by a responsible adult is likely to be challenged from somewhere; it isn't as though sexual activity were different from any other area of conscious choice. And to challenge behaviour may be deeply unwelcome and offensive in a personal sense, but it is not a matter for legislative action.

A local branch of the Campaign for Nuclear Disarmament is likely to assume that the manufacture, possession and use of nuclear weapons is wrong; a religious member of such a group will probably say that it is "sinful". It would be surprising, though, if this meant that such a group could be accused of public offence because it disagreed strongly with the moral options made by Ministry of Defence officials, employees of various industries or indeed government ministers. A good CND member would no doubt say that all such people were to a greater or lesser extent involved in evil, even if the exact degree of conscious individual responsibility for such evil was unclear.

This is very uncomfortable, no doubt personally offensive, for any civil servant or politician to hear; but is it the sort of offence that merits legal sanction? The answer is obviously no - unless the imagined CND member were to go on to say that the options and acts of the civil servant or industry worker or politician put them forever outside the fabric of lawful society and made them legitimate targets for harassment and violence (the case of some animal rights activists illustrates that this is not just an academic possibility). The law steps in only when someone's basic security is threatened. But it does not step in to say that CND has no right to make moral judgments on the options and acts of those who maintain the nuclear industry. If it did, we should rightly complain that certain fundamental freedoms were being infringed. Nor do we expect the law to insist that any and every official position in a CND branch should be open to persons of no particular convictions about nuclear weapons, or indeed to supporters of the nuclear deterrent. CND is a society with an intrinsic right of association, and it can properly determine what its rules are and what conditions of membership it should lay down. If you don't like it, you are free to oppose it by any legal means - to argue against its tenets, to try to resist its influence, to go along to open meetings and ask unwelcome questions.

This issue about the right of association is a significant one on a wider stage. In society at large there is always - especially these days - a tension between those who think that the job of the Government is to manage and seek to reconcile the actual diversity of flesh and blood communities of people with different convictions, and those who think that the Government has to dismiss all particular convictions to the private sphere so as to secure a neutral space for everyone in which no unlicensed ideas or images appear. The latter position is always drawn towards the conclusion that it is for the state to decide what groups may exist within its boundaries and what the limits of their activity should be. But this assumes that rights of association are actually quite restricted and that they can be given or withheld at the will of the Government. The former view assumes, in contrast, that it is the plurality of associations that "comes first", so to speak, so that government is invited by diverse groups to manage their relationships and mediate when there is conflict. Put like this, the contrast is too sharply drawn, of course; but it helps to focus the underlying problem.

Do human beings have the liberty to associate on the basis of common projects and common convictions independently of the state's licence?

Most committed democrats would answer yes, on the understanding that those projects and convictions do not in themselves threaten or disrupt the lives and liberties of others. Many would go further and say that these diverse associations are vital to the health of a society and can co-operate with the organs of central Government to promote the good of all in certain circumstances. The mere expression of a controversial belief, independently of any evidence of violent and disruptive results, should not be grounds for suppression.

The parallel with the student union context ought to be clear. Presumably, student bodies begin as free associations, which collaborate for certain common purposes through an organ like a students' union. The union itself doesn't, or shouldn't, have an agenda of its own that is in competition with the associations involved. A union recognises student societies, but doesn't create them as a "franchise". So in this case, the question that ought to be asked is what those student unions that have sought to withdraw recognition from Christian unions think their powers are; do they see themselves as "brokering" the business of a wide variety of bodies, many of whose views they (naturally) do not endorse? Or do they think of themselves as representing a central authority that can create or abolish associations? Do they think of themselves as something like the British Government as it has generally worked, or something like a Napoleonic system where central administration decides the liberties of subordinate bodies?

Christian unions, like most student associations, can be a nuisance. As a university chaplain many years ago, I was blessed with good relations with members of the Christian union, thanks to the maturity and warmth of the local leadership; but I know that not every chaplain in higher education has the same good fortune. Questions about tests for orthodoxy recur regularly in the histories of Christian unions, and every few years there is likely to be some degree of conflict and sometimes schism (as in other societies - I can also remember the ferocity of debates in the 1970s within a university Labour Club at the time leading up to the formation of the Social Democrat Party). Furthermore, there is real debate and divergence among Christians about the ethics of same-sex relationships, and some more liberal Christians will find it embarrassing that the traditional position of the Christian union can be seen by the rest of the student world as something like an unquestioned Christian line. Christian unions can appear detached from the rest of student life in some campuses (by no means all); or they can lay themselves open to charges of insensitive recruitment; and so on.

But the basic question remains. Is there a straightforward right of association for people with these convictions?

Let me go back to my starting point. The danger in issuing sanctions against a body whose views you disapprove of is that it looks like a fear of open argument. If disagreement is to be silenced because offence may be caused, that is not good for intellectual life; it personalises and "psychologises" all conflict of ideas and denies the possibility of appropriate detachment in debating issues. As I said earlier, there is such a thing as offence that is and should be legally actionable, offence that so undermines basic human respect that it in effect denies a person's or a group's dignity and puts them materially at risk. But a moral challenge to someone on the grounds of their choices is a tribute to human dignity: if I challenge what you do, I take you seriously as a moral agent, a free person whose choices matter, whether they are about sex, money or whether to take a job in the MoD. A good institution of higher education is one in which students learn that their questions are not everyone's questions, and their answers are not everyone's answers.

Simply in the fact of being alongside people who are following other academic disciplines, you learn that different people want to know different sorts of thing. You learn that your world is not the obviously right and true one just because you say it is. Whatever convictions you emerge with will have been tested by this critical exposure to other ways of seeing and other sorts of investigation.

It would be very bad for such a climate if the idea were allowed to gain ground that a student union could be an arbiter of publicly acceptable belief, saying "yes" or "no" to this or that position. All very well when exercised in "liberal" causes, you may think; but students are as volatile as anyone else and as susceptible to manipulation: what happens if other views become dominant?

So this is not quite a storm in a teacup, nor is it simply about anti-religious prejudice looking for a soft target. It touches some basic political questions as well as raising issues about the ethics of education itself. No doubt some Christian unions might do well to undertake a little hard self-examination about whether their language is vulnerable to proper challenge; they may need to affirm more clearly and credibly the distinction between declaring behaviour unacceptable and in effect passing judgment on a whole category of persons. But that does not alter the fundamental point about freedom of association. The integrity of the whole educational process in a democracy depends on getting this right, and it should not be obscured by hasty and superficial reactions to what are regarded as unacceptable opinions by the fashion of the day.

© Rowan Williams 2006