The most severe critics of Sajid Javid’s decision to revoke Shamima Begum’s UK citizenship say that he effectively killed her baby. Anyone who saw her TV interviews will have found her hard to like. Some of her comments supporting terrorist attacks were monstrous. But people who have been recruited into cults believe and say monstrous things. It does not make them monsters – the real versions of themselves and everything they may have believed were destroyed when they were radicalised or, to use an old-fashioned term, brainwashed.

Four years after Begum was indoctrinated into Islamic State, the teenager showed all the signs during her recent interviews of having been under cultic influence. Her head was tilted down, she used monotone speech conveying no emotion and her manner was detached and cold. When she did eventually look directly at the interviewer, it was clear that the windows to Begum’s soul were long closed. The most damaging thing she said that secured her banishment from her homeland was that she “wasn’t bothered” by the sight of severed heads in bins in Syria. She spoke as if what she was saying was totally normal, as if expecting sympathy.

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Desensitisation is a key part of the process for cults recruiting people to commit abhorrent acts – emotion would hamper willingness to take life, so it is suppressed. Young female recruits to the mujahideen in Pakistan in the 70s were shown films early on in the recruitment process of other young women blowing themselves and others up, prompting severe distress. By the end of the first month the discomfort was lessened. After three months the viewers didn’t bat an eyelid. Violence is normalised.

In recent years cult experts have become interested in highlighting the parallels between how cults such as the Moonies recruit new members, and how terrorist groups use exactly the same methodology and psychological manipulation to secure unswerving commitment. No one “joins” a cult – they are targeted and recruited. They are lovebombed initially, as part of the grooming process. They are seduced, told how special they are, told what a difference they could make to the movement. Then every argument they put forward for not believing whatever is being asked of them is carefully taken apart, bit by bit. With great skill on the part of their manipulators everything they believe is replaced with the ideology of the group.

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Those who ask questions are doubters – they must believe wholeheartedly, or they are useless to the movement. They are accused of vanity or arrogance if they resist, shamed into submission. They are then encouraged to either recruit their families and friends, or cut all ties with them. Non-cult literature is banned, as is television, sometimes music and art that isn’t on the cult’s approved list – anything that isn’t promoting its core values. Soon the new convert’s entire world is controlled by the group, and everything they do from what they eat, what they wear and who they have relationships with is subject to approval by the cult’s leaders. Arranged marriages such as Begum’s are common, as a means to secure total commitment from emotionally vulnerable young female members.

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Begum was just 15 when she had her head turned by Isis. Intellectually curious, alert, idealistic young people generally make easy targets, and they are the ones that stop in the street when Scientology recruiters invite them to take a “personality test”. They are the ones who ask probing questions, who are open to debate, and this makes them vulnerable as the recruiters have their ear. Their trained manipulators have been doing it a long time, using tried and tested techniques. They have an answer for everything. Who knows what resistance if any Begum may have shown? One thing is sure – she was ripe for the picking.

Elsewhere in Europe the use of undue influence or “mind control” is illegal, but in the UK we don’t recognise it as a crime. The process of indoctrination can, however, be reversed. It is commonly referred to as “exit counselling”, and when it happens – it’s often hard to get a cult member alone for long enough – it is often successful. If Begum had been allowed to come home, she could have been helped to recover her critical mind. She could have been useful to the government by providing intelligence about her former terrorist associates.

There can be no doubt that Isis is a cult. Governments now must start to accept that recruitment into terrorist groups is the same as getting targeted by any other cult. It’s a process, not a lifestyle choice. As long as we continue to believe as a society that young women such as Begum have made a decision to run away to Syria to help terrorists, we will remain no closer to understanding this behaviour or to preventing it.

• Lynne Wallis is a journalist specialising in how people are recruited into cults, and how they can recover and reintegrate back into mainstream society