Last weekend the Mayor of London, Sadiq Khan, described the massacre in Christchurch as the result ‘of failing to root out Islamophobia and anti-Muslim sentiment from our society’. His intention is to crack down on Islamophobia and give it a formal definition. He is right about anti-Muslim sentiment. But he is dangerously, terrifyingly wrong about Islamophobia.

It has become common to hear the New Zealand atrocity described using this word, but it is loaded with sinister implications that the vast majority of well-intentioned people will simply not understand. And the reality is that it plays straight into the hands of the jihadis.

The Christchurch attack was not an act of Islamophobia. It wasn’t a religion that was gunned down in Christ-church, but the followers of that faith. The mass murderer hated Muslims, and wanted to kill as many people like me as possible. He acted from virulent, lethal, anti-Muslim xenophobia — not from Islamophobia. The difference between these two terms is not one of semantics. This is about the fight between mainstream Islam and the jihadist imposter, a fight in which words are weapons.

Islamists deploy ‘Islamophobia’ as a political and judicial shield to protect them and defame their critics. Their creed is Islamism, a modern-day political agenda masquerading as religion. Its artefacts take the form of permanent war with secularism and an obsession with purity as the external symbol of overt religiosity: the untrimmed beards, the women forced to wear the niqab and the abbayah — along with the profoundly undemocratic and un-Islamic concept of blasphemy

These are drawn not from Islam but a 20th-century totalitarianism. The notion of prosecuting blasphemy or even apostasy has no scriptural basis in Islam: while disbelief is mentioned more than 150 times in the Quran, an earthly punishment is not. If indeed defamation of Islam or eschewal of belief in it is a crime, the Quran designates it a matter strictly between the mortal and his Maker. Hardly the scriptural framework for prosecuting Islamophobia.

Centuries of records show hardly any such criminal cases prosecuted by Muslim jurists. Islamic scripture, whether the Quran or the Hadith and related writings do not show a history of Islamophobia either. There is a record of a Christian tried for blasphemy because of insulting the Prophet Mohammed in Damascus in 1293 but he was acquitted by the jurists of the time.

In his masterpiece Islamism and Islam, the Damascus-born scholar Bassam Tibi explains how political zealots managed to pass off their inventions as tradition. ‘By presenting themselves as the spokesmen of true Islam,’ he says, they ‘have enabled themselves to defame their critics by the equally invented notion of Islamophobia’. This word, he continues, ‘serves as a weapon against all who do not embrace Islamist propaganda, including liberal Muslims’.

This weapon is all the more potent when in the hands of naive but well-meaning westerners who seem to think they are helping Muslims. The Algerian novelist Kamel Daoud found himself — an Arab Muslim — targeted in this way after the New Year’s Eve sex attacks in Cologne, where gangs of North African immigrants molested women. They had arrived, he pointed out, from ‘an Arab-Muslim world full of sexual misery, with its sick relationship towards women’. For this, he was attacked in Le Monde by French intellectuals for ‘feeding the Islamophobic fantasies of a growing part of the European population’, thereby silencing him from opinion journalism and depriving France of important insights from a mainstream Muslim voice.

When Boris Johnson said that those dressed in niqabs looked like letterboxes, he was subjected to a formal investigation by his own party. Did the Conservatives fail to understand that there is absolutely nothing Islamic about the niqab? It is so peripheral to Islam that Muslim women are banned by Islam from wearing it at Hajj, the pilgrimage to Mecca and the highest religious rite Muslims can perform in their lifetime.

To talk about ‘anti-Muslim bigotry’ or ‘anti-Muslim hatred’ might be clumsy phrase-ology. But if this is what you mean, then these are the words you should use. There is enough of it about. Take Fraser Anning, an Australian senator, who — on official governmental letterhead and within hours of the Christchurch killings — decided to ‘highlight’ the ‘growing fear’ of an ‘increasing Muslim presence’. His clear implication was that all Muslims are inherently a threat. This kind of bigotry is not hard to recognise or condemn. Nor does it require a new law.

All of this matters because, while we’re getting better at thwarting terrorist attacks, we’re still fighting their ideological underpinning. As a secular pluralistic democracy, we have weapons: intellectual scrutiny, critical thinking and above all the insight to command the language of this war of ideas. And to use the word ‘Islamophobia’ when talking about anti-Muslim xenophobia is to use the vocabulary and adopt the rulebook of the Islamists who wish to obfuscate their intent.

Sadiq Khan wants the Tories to define Islamophobia as ‘a type of racism that targets expressions of Muslimness or perceived Muslimness’. This definition would go down well in any autocratic Islamist regime, as it is so wide-ranging that it could apply to almost anyone or anything — even Khan has been accused of Islamophobia. So the Mayor should be careful what he wishes for. If he gets his way, the jihadis would be delighted. It would be tragic if, in an attempt to protect Muslims, we ended up taking the jihadis’ bait.