The horrors with which ISIS deals with apostates, homosexuals and sundry offenders against the primitive Sharia 'law' clearly have no place in the 21st century and are beyond any understanding or excusing. These Moslems are barbarian unenlightened natives, immersed in the stupidity of religious bigotry. As members of an evil death cult they have already consigned their souls to Hell.
However, their activities are not without parallel in our own pre-enlightened past. During the Thirty Years War in Europe the phenomenon of witch-burning peaked; previously very rare, and after around 1650 rare again, but during the war period at least ten thousand women were condemned and burned alive in Europe - by both Protestant and Catholic authorities.
The First and Second Enlightenments changed everything. European men since are not the same as men before, nor churches since the same as churches before. It is specious therefore to claim, as some feminists or atheists do, that either men in general or religious men in particular are still liable to incinerate gobby, clever or independent women. Witch-burning was never an individual psychopathic activity - it was a participatory sport in which men used their pre-enlightenment understanding of their faith to justify their collective barbarity. And that phase has now long passed from European mandom.
However, the same primitive behaviour is still apparent both amongst ISIS in Syria and Iraq and primitive men of Pakistani or Bangladeshi origin, nearly all Moslem, in our own towns and cities. Their violence and sex crimes are not secretive, individual acts of delinquency but a collective, participatory sport with self-justification from their primitive and unenlightened understanding of their own faith. Sixty Moslem men raping a twelve year old girl in Aylesbury, throwing a gay youth from the roof of a building in Raqaa or sawing the heads from their terrified captives are all part of the same problem - that we are not, as enlightened Europeans, dealing with our equals but with those no different to our own ignorant, unenlightened ancestors four hundred years ago.
So no. We cannot allow Islam to be the equivalent in our society of Christianity until it has passed through the same enlightenment, undergone the same changes. Until then it is the unacceptable primitive faith of killers and abusers.