Words have emotional impact. To be accused of discrimination, for example, will usually provoke a chilling feeling and a defensive response. But what if someone calls you discriminating? That’s a warm glow word. As an academic, I rather like it if someone reviews my work using that word. It makes me feel knowledgeable and wise; someone who can make insightful distinctions.

Listening to a Radio 4 debate on faith schools the other week on the Beyond Belief programme, it was striking how prominently the D word figured in the discussion. Discrimination that is; not discriminating. Opponents of faith schools know full well its emotional impact.

When does discrimination become a discriminating act? The answer is when the criteria used to make the choices involved are relevant to the choice in question and are beneficial to the activity being pursued. It is, for example, discrimination to object to a lineswoman at a professional football match on the grounds of her gender. It is, however, discriminating to object to someone having the job if they really don’t understand the offside rule. Gender is irrelevant in this case, knowledge of the rules of football is not. A football match quickly descends into anarchy if the officials are clueless about the rules.

One of the main objections made against faith schools is that they are allowed, in some instances, to take account of people’s religious beliefs when appointing staff. That is clearly discrimination, or so it is thought by their opponents. For that to be true however, religious beliefs, like gender in the case of a football official, have to be irrelevant to working as a teacher. But that can only be the case if religious faith is irrelevant to the commodity in which education trades, namely knowledge. And this is where we hit a disagreement.

A secular view of life regards religious belief as irrelevant clutter when it comes to knowledge; something essentially private which religious people insist on adding unnecessarily to the things that all rational humans know. Why, for example, add God to the equation when the theory of evolution gives us all we need to understand the development of life?

By contrast, most religious views of life don’t see their beliefs as add-ons. For them, those beliefs are the foundations of their understanding of the world. If the secularists are right, choosing staff on the basis of their religious faith is discrimination because it is making a choice on the basis of an irrelevance. For the religious people, however, to include consideration of religious faith as a criterion in staff selection is to be discriminating because the ethos of the school depends on employing people who understand and support that ethos.

So who is right? That question is the subject of ongoing debate. But what seems clear to me is that to insist that religion is irrelevant to education is to adopt a secular view of knowledge. For the public system of education to be built on the premise that religion is clutter is discrimination, because it favours a secular view of knowledge when there is no good reason to do that.

Please do not misread me at this point. I am not arguing that every teacher should be selected to conform to the religious ethos of a faith school. I am simply saying that religious faith is a relevant factor to consider in staff appointments in a faith school if the school is to achieve its goals and develop its ethos. This may have strange consequences.

For example, a student at ChristChurch recently asked me how I would view her as an applicant for a teaching post if I was head of a church school given that she was an atheist. I had no hesitation in replying “as an asset”. In modern Britain it is unquestionable that all schools must prepare their students for living in a society where disagreement over religion is a fact of life. It therefore seems obvious to me that schools, even faith schools, need to appoint staff to reflect that diversity. That makes consideration of applicants’ religious and non-religious beliefs a very relevant factor in making appointments. A discriminating faith school will therefore seek to appoint staff taking account of their beliefs to ensure balanced representation of its own ethos and of the diversity in society at large.

Trevor Cooling is Professor of Christian Education at CanterburyChristChurchUniversity.