"Faith schools dont just select on faith or their wouldn't be 30% of non catholics being educated within catholic schools."
Some faith schools have some "community" places, where a proportion of children are admitted on distance rather than faith.
Some faith schools are 100% on their criteria, with faith at the top, and if there are enough children of teh "right" religion applying, then the school has 100% students of that religion.
In the area I live in, more than 60% of the state primary schools select on faith, most of them have no "community" places. If you are the "wrong" religion or go to the "wrong" church then you are a bit stuffed really. The faith schools in our area are CofE, Catholic and jewish. If you are not of any of those faiths then in some cases you have a real problems.
People need to remember that the situation is different in different parts of the country, and thst different schools have different criteria and ethos. They need to investigate fully what the situaiton is where they live. And not blithely dismiss anything outside of their personal experience as rubbish 
fastedwina I am a lapsed catholic, was raised a catholic, went to catholic school etc etc yada yada. Please don't assume that anyone who disagrees with you is not catholic. Assumptions about other people and their lives and experiences are never a good thing.