In the US you've got public schools, where religion isn't taught (due to seperation of church of state...though saying that it's not taught is kind of misleading, I'll go into it in a bit), private schools (often high schools that concentrate on a specific subject -- math&science or the arts are the usual ones...though sometimes they're just a private school that's not a religious one), and parochial schools (which for the most part are Catholic). I went to a public high school, but I had nearly gone to a private high school that concentrated on the arts (too far away and too expensive, though), and I had a number of friends that went to Catholic school.
From what I understand, at Catholic schools they have prayers and such every day and church services, but they also learn about other religions, too, and you're not required to be Catholic to attend one -- one of my friends who went to a Catholic high school was a downright atheist. But no one can deny that for the most part, they ARE the top of the US school system.
When I said that religion isn't allowed to be taught at public schools, though, that isn't quite 100% correct. Basically what seperation of church and state means is that in a public school, you're not allowed to set aside time during the day for prayer, not allowed to teach that one religion is better than another, etc. If you're in a philosophy or history class, though, religion will come up, especially if it's a world history class. I took European history, Eastern Asian history, and US history, so I learned bits about Christianity, Judaism, Islam, Buddhism, Confucious (I think I spelled that right), Shintoism...etc. But what we were taught about these religions or philosophies what basically how they started out, how they effected history, their influences on cultures, and their influences today. We only learned a brief outlining of each religion/philosophy's beliefs (and I remember many the debate in my Asian studies class about whether or not it is possible to actually achieve Nirvana...but I'll not go into that). This, I believe is necessary for a history class, because if you know a bit about an area's religion or philosophy, it helps in understanding the culture and people and history of that area.
But do I think that there should be schools that teach only one religion, excluding all others? No.