They are fleeing Latifiya – a city just outside Baghdad – in their thousands. A few months ago, it had a population of 200,000, but now only 50,000 remain. This is a town of horror. According to Human Rights Watch, Islamist militias are summarily executing civilians. People are being taken out of cars, ordered to kneel on the pavement, and then shot in the head. On 11 June, 137 men were seized from the town’s Um Weilha market. Thirty bodies have so far been recovered; the fate of the others remains a mystery.

More compelling evidence of the need for western air power to pummel these barbarians, you might think. But the persecutors here are not Islamic State (Isis). They are Shia fighters under the control of the former, western-backed prime minister Nouri al-Maliki, whose violent sectarianism did so much to fuel the rise of Isis. They are murdering and torturing Sunni Muslims, victims whose lives have been deemed to be of no significance. As Human Rights Watch points out, “their stories are falling on deaf ears”. No white westerners were forced to recite chilling messages in professionally made videos before being murdered, so no horror is expressed by western politicians. There aren’t ever louder and more irresistible calls to “do something”; there are no parallel denunciations of opponents of western intervention as deluded peaceniks or heartless isolationists.

None of this is to understate the barbarity of Isis. A confession: I’ve had nightmares about it and have spoken to friends who have too. It gets to you, Isis – it’s running what must be one of the most sophisticated programmes of psychological warfare mounted by a terrorist group in history. Partly through a social media campaign that is more advanced than those run by many corporations, it is transforming us into its recruiting sergeants.

We grow more terrified of it; we express our terror, and so help to spread it. Western media compete over inflammatory language to express the evil of Isis, and add to its almost otherworldly, terrifying mystique – a mystique Isis has depended on to conquer large swaths of Iraq and Syria, because its opponents are left too frightened to resist. Stills of its videos are plastered across the media, and vicious anti-Muslim diatribes are posted on Twitter – which must delight Isis: the more hatred of Muslims ratchets up, the better chance it has of winning support.

Some belated realisation that we are simply following Isis’s script is filtering through. This week’s Independent on Sunday front page featured white text on black, defiantly refusing to display Isis propaganda. Social media abounds with calls to share pictures of the murdered Salford taxi driver Alan Henning hugging a Syrian child to showcase his kindness, rather than his last moments, as Isis would want. We agonise over what to call the jihadis: why should we call them Islamic State, as they would wish, when they are neither?

The fact is, we are playing the part Isis has written for us in an even more profound way. “We must do something” has too often proved to be the cry of a man pouring a can of petrol over a burning home. Isis knows that, which is why it is doing everything it can to incite western intervention. “Is this all you are capable of doing in this campaign of yours?” mocks the spokesperson Abu Muhammad al-Adnani. “Are America and all its allies unable to come down to the ground?”

A British jihadi has called for the UK to “send all your forces” so Isis can “send them all back in coffins”. In the upsetting propaganda videos he has made under duress, the British hostage John Cantlie says Isis cannot be defeated by air power, but only with ground forces. As General Jonathan Shaw – the former assistant chief of the defence staff – says: “What possible advantage is there to Isil [Isis] of bringing us into the campaign? Answer: to unite the Muslim world against the Christian world. We played into their hands. We’ve done what they wanted us to do.”

Far from stemming its advance – aside from limited early achievements, particularly recapturing Mosul Dam – since the bombs began to fall, Isis has continued its onward march. Heet, near Baghdad, is believed to have fallen; Isis could already be within artillery range of the capital; and it appears to be on the verge of seizing the northern Syrian town of Kobani. In the initial phase of bombing, Isis is believed to have added 6,000 recruits to its ranks. Its “growing online support intensified” after the bombing raids, says the FBI director, James Comey. The al-Qaida-linked al-Nusra Front abandoned its hostilities with Isis, calling for an alliance to take on the Americans. Last Saturday, the Pakistani Taliban declared their support for Isis and called for their sympathisers to join its struggle. Isis is stronger now than it was before the bombs began to fall.

So what can be done? At the moment, many Iraqi Sunni Muslims prefer Isis to the sectarian Shia militias. Until that is addressed through a process of national reconciliation and by integrating the Sunni minority – reversing the damage done by Maliki-style sectarianism – little will change. Jihadis have previously been turfed out by Sunni tribes, but there must be confidence in what replaces Isis.

Murderous Shia militias must be dismantled. Kurdish peshmerga must, undoubtedly, be properly armed. The western-backed dictatorships of Saudi Arabia, Kuwait and Qatar must be compelled to crack down on the funding networks that are helping to sustain Isis and other terrorists. As General Jonathan Shaw says, these western client states must stop exporting the Wahhabi/Salafist ideology that underpins jihadi terrorists everywhere. Economic sanctions – and certainly arms embargoes – must result from non-compliance. External military intervention in Iraq and Syria must be led by regional powers, not by western forces as Isis craves.

Will common sense prevail? Unlikely, given the more-than-understandable revulsion that has swept Britain and beyond since the brutality against Alan Henning. But that, of course, is what Isis intends.

We cannot bomb an ideology out of existence. One can only imagine the satisfaction among Isis’s ranks that we are following a script that it has written to the letter.