where is your evidence that half of Moslem children become non religious?
Actually I didn't claim that hence:
'But to non-religion, well that is another matter. While we may not yet be in that territory there is no reason to suppose that forth, fifth etc generation muslims will adopt a similar pattern of religious transmission over generations as christians (and indeed jews) currently do.'Actually the research I have seen suggests that intergenerational transmission of religion in UK muslims is about 75%, so somewhat higher than for christians, although I suspect this will decline over generations.
However the point isn't the absolute level of intergenerational transmission, but the gap between transmission of religion and transmission of non-religion, which we know to be pretty close to 100%. So it might take a little longer but you still end up with more non-religious offspring than religious from a starting point that is 100% religious.
So let's take a model example - two muslim parents, let's add the following assumptions:
1. Each has four children
2. Intergenerational transmission of islam is 75%, with the remainder becoming non-religious (as we know intergenerational conversion from one religion to another is tiny)
3. Intergenerational transmission of non-religion is 100% (I know it isn't quite 100%, probably 97% but this makes the maths simpler)
Starting generation - 2 people, 2 muslims - 100% muslim
First generation offspring - 4 people, 3 muslims, 1 non-religious - 75% muslim, 25% non religious
Second generation offspring - 16 people, 9 muslims, 7 non-religious - 56% muslim, 44% non religious
Third generation offspring - 64 people, 27 muslims, 37 non-religious - 42% muslim, 58% non religious
So by the third generation there are more non religious offspring than muslims.