Allegations that 25 schools in Birmingham are at risk of an "Islamic takeover plot" reached new levels of hysteria recently. An announcement was made that a counter-terrorism expert has been drafted in to conduct yet another investigation. The minister responsible, Michael Gove, has managed at a stroke to increase fear and suspicion between Muslim and non-Muslim in the city. The fact that the chief constable of West Midlands police, Chris Sims, has denounced the decision as "desperately unfortunate", itself an extraordinary move, gives an indication of the scale of the concern.

So what was the evidence that provoked such a serious intervention and the accompanying media frenzy? A four-page document in which "plotters" outlined their dastardly plans to oust a headteacher for not being "open to our suggestions of adhering to strict Muslim guidelines".

It made reference to a headteacher called Noshaba Hussain, whom the alleged plotters claim to have ousted from Springfield school only for her to be reinstated by the governors, and so "we have another plan in place to get her out". But the school has confirmed that Hussain left the school 20 years ago. Other details point to the document's inauthenticity and Sims – the most senior police officer in the region – has told the Guardian that it could be a hoax.

Governors at the schools concerned have strongly rejected the allegations. David Hughes, a governor at Park View school for 15 years, wrote an open letter to Michael Gove and condemned "the witch-hunt against the most successful school of its characteristics in Birmingham … under the pretext of concerns about extremism and threats to the education of our pupils". Just last year Park View School hit the headlines for achieving an "outstanding" ranking from Ofsted despite a few years earlier being one of the worst performing schools.

Muslim governors challenging the narrative meet with accusations of denial and complicity. Many have worked hard for over a decade in partnership with teachers to turn schools around. Muslims feel under siege, while being accused of besieging an unwitting and overly tolerant majority who in turn will be fearful and mistrustful.

The real scandal is how scepticism over this "dodgy dossier" seems to have been thrown to the wind. What is more heartening is that local people are coming forward to stand in unity. The Rev Oliver Cross, who also happens to be vice-chair of governors at Regents Park school, one of the schools named as among those "infiltrated", has categorically refuted the allegations and called the appointment of Peter Clarke a "disaster for community cohesion". He says Birmingham Muslims are now "used to accusations of 'Islamism' or 'extremism' being hurled at them, not because such things exist, but for the simple crime of being Muslims".

Different opinions may well exist among Muslims around schooling: the conservative-liberal spectrum of opinion is not unique to us. Since when do concerns by religiously conservative parents about teaching on homosexuality, girls and boys mixing, and the reciting of prayers, require anti-terrorist experts to get involved?

This latest investigation comes after the government announced that British affiliates of the Muslim Brotherhood will be investigated, and the Muslim mayor of Tower Hamlets was described in police reports as an "extremist". When those who make criticisms of foreign policy get accused of creating the mood music for terrorism, there is understandable frustration and despair. Increasingly Muslims feel they just can't win. On the one hand we get told we are not integrating enough and we should engage more in civic society. On the other, when we do, we get accused of having sinister agendas. There is more than a whiff of McCarthyism in the air. Chris Sims says he is concerned about the impact this will have on community cohesion. He is right to be.