I'm not sure how religious studies helps children to understand the history or culture of any country, these lessons are still about the teachings of christ, creationism etc..
I don't allow my children to do religion in school but my youngest when 4, I allowed him to be in the religion class to help him with the language, I knew he'd understand very little of the lesson, plus it helped the school, as they didn't have to find someone else to look after my son..
until one day I happened to see the religion book on a parent-teacher day, there was a picture of a child brushing his teeth with god in the mirror telling the child that god knows if you don't brush your teeth,
so that was that, I stopped my son from doing religion, I just can't allow this sort of mumbo jumbo into their lives..
edit... I should add catholic teachings..