I think the rather fundamental issue you have missed is that we need to be able to criticise all religions and their practices openly and without repercussions.
Afaik there have been no beheadings of people In Europe for criticism of Christianity. There are no teachers still in a police protection scheme after several years for making an unguarded comment about God.
Of the 66,000 girls in the UK that the government says are at risk of FGM, the tiniest proportion are from a Christian background - the rest are Muslim.
The vast majority of sane British society take a very dim view of first cousin marriage (the only people I’ve seen arguing in favour are on here bizarrely), especially repeated through generations despite the significant number of severely disabled babies produced.
The government are working with the Muslim Council of Britain in a definition of Islamophobia to be brought into law that will stop us criticising ‘expressions of Muslimness’. That will shut down free speech and make it far harder for us to call out unacceptable behaviour.
I’m not sure why you are so determined to minimise the obvious harm caused worldwide and in the UK in the name of Islam by constantly saying ‘well Christians do it too’. We criticise the relatively small number of fundamentalist Christians that may operate in far flung countries. We need to be able to criticise some Muslim practices worldwide and here too.