If youre Catholic..
I'm not Catholic and I went to Catholic schools.
I didn't have a problem, and neither did they. I could parrot back the words I was tought in Religion class and they didn't mind that I didn't believe it.
There weren't any Jews in my school that I knew of, but a fair number of Protestants.
We would have gone to the Episcopal school but Dad couldn't afford it and couldn't see the difference was worth the money.
Shalom.
The Catholic School system also works.
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If youre Catholic..
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Nearly all Catholic schools accept students of any or no religious affiliation.