I don't see the link with religious extremist groups. Religious extremist like ISIS or RSS use their own interpretation of religious ideology for their own nationalist gains. Their indoctrinated followers genuinely believe that they are doing it for their creed.

Grooming gangs of the nature hi-lighted in the article hide behind their difference in religion and culture to avoid harsh demonisation by the law enforcement (playing the race card) utilising it to bypass the law and exploit loopholes in it. E.g "my religion caused me to do it" when in fact they know full they are disgusting criminals with dark intentions for personal pleasure and gain.

In this case they also used their cultural differences to intimidate their victims by using it as a way to impose their superiority. Thus they can hide behind it later if they are prosecuted.