My 3 sisters and I all went to Parochial schools when we were kids. The education we got was definitely better than the local public schools. I left that system after 9 years and finished in a public high school around the corner from our house.
The english, math, and science classes there were almost 2 years behind the private schools. Finishing school there was a piece of cake because I had already been taught what they were teaching there in those subjects.
My sisters all went to private school for 12 years, but after 9 years of that crap, I couldn’t deal with it any more.
The religion aspect had no affect on my beliefs.