Actually, I didn't attend a "Christian" school. Normal schools are like that here in Britain - everyone, regardless of religious faith, sings those hymns in primary school (up 'til you're about 12). I went to private school for a couple years and they had to sing them in high school too. As I remember it, my primary school religious education was very Christianity-focused as well. The payoff is that once you get to high school it's much more multicultural and pluralistic.