In a multi-cultural society individuals should be free to follow there chosen religion but not have someone else's beliefs foisted on the children. Children from different communities should be able to mix freely as the grow up. For school to be able to provide a rounded education there must not be artificial segregation imposed on them by the state.
Followers of different faiths are free to educate there children about their religion out of school hours. Religious schools are divisive (look at N Ireland). How many different religions would need to be catered for to be fair to all minority? Are parents teaching their children to he hypocrites to get them into a church school because it had a good educational recored?