Okay, I'll try to give another view -- I'd just been lurking here, thinking, 'Oh no, don't want to get controversial, everyone'll hate me...'
My children are at a Catholic school, where (at least in principle) all the children come from practising Catholic families. In theory there are places available for non-Catholics or even non-Christians, but in reality the school is so over-subscribed that this doesn't happen. There is very good racial and linguistic diversity about half to two-thirds of the children are from ethnic minority backgrounds and about a third of the children are on free school meals. About 10% of the kids have some form of social services involvement, and some come from very difficult backgrounds -- eg. parental drug-taking/selling, violence, prison etc. Another 10% or so come from very comfortable professional middle-class backgrounds.
The school is a successful, very caring and safe community in a difficult area, which does its best for all the children. The league table results are reasonable, although not stellar, and the children are happy and achieve as well as they can.
Part of the reason for the school's successful atmosphere is that many of the families are regular attenders at Mass in one of two local churches, and are otherwise involved in parish activities. This shared faith and values is a cohesive factor in a very diverse community, and has a very positive effect on the children's sense of stability and security. In addition too this, the faith and values taught in the school back up those taught in the children's homes.
I know that many non-religious schools are doing a successful job in similar communities without the religious factor. But for me the fact that the children see their classmates and their teachers sharing in the practice of the faith they are taught at home is a very important factor in supporting the way we are bringing them up, and I know that many other parents who have chosen to send their children to our school or similar schools feel the same.
However, this kind of shared religious experience is appropriate only where you can assume that all the families share the same religious outlook, which is clearly no longer the case in rural areas where there may be no effective choice of school.