Personally I'm not suggesting that there are crazed ambitious middle-class parents lying to get their kids into pushy little exam factories -- I mean, probably in some areas there are, but I don't have any experience of that so I'm not going to sound off about it.
I went to a Catholic school rather like the one you describe (well, it was like that when I went to it although the lovely nurturing atmosphere had dissipated by the time my siblings got there), and my mother teaches at another very similar. I think I have a fairly realistic view of church schools.
I call your attention, though, to the word "chose" in your post. You could look at the two state schools in your area, think "ooh, that one has children that DS is friendly with, a lovely nurturing atmosphere, etc., etc." (yes, some of the etc., etc. is religious-based, but not all of it by any means) and choose to send him to it. I have three state schools in my area and get to think "OK, he can't go to that one, can't go to that one, so I guess it'll be that one then". There is no element at all of being able to think about friends, nurturing, family, environment or any of that, or try to make the decision that is right for DS (well, there is to an extent, because we are probably going to go private which is not something I ever thought I'd do).