Thanks for the info Piscesmoon - I'm new to all this (and hence naively shocked at how the system works) as DD is only 2 and I haven't worked in education.
I think I understand from what you say that catchment is always the first decider for whether a child gets into their preferred primary, is that right? Then if that preferred primary is oversubscribed, and it is a church primary, children who don't come into the catchment but still want to go there may be selected for on the criteria of whether their parents are church-goers?
So - for example - Family A and Family B might live next door to each other, just outside the catchment for state primary Church School C. The parents of child A and child B would prefer that their children attended School C for a variety of reasons, eg it might be on the way to the parent's workplace, near a grandparent / other childcare, best friends are going there, good Ofsted results etc.
Family A are church-goers, and Family B are not. I can see why Family B might be 'het up' about the fact that their child will face discrimination and disadvantage as to choice compared to Family A's child purely on the basis of the parents' church-going (or lack of). It is after all a state primary, and Family B are tax-payers too. I can also see why Family A might shrug and go 'well I don't know what all the fuss is about, it's a church school'.
Personally I think it is wrong that children face discrimination with regard to certain state services because their parents either don't practise the 'right' religion or don't practise any at all. And quite bizarre that parents are put in the position of pretending to be religious in some cases.
Onager - yes I'd agree with integrating a wide variety of cultural ceremonies, in the form of plays, dancing, crafts, story-telling etc - sounds valuable in terms of helping to understand the world they live in.