I went to a christian brothers (catholic) school
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Thankfully we had decent science teachers, great physics teachers and biology was only ever taught in view of evolution. None of this make believe fantasy creationist garbage. We even had comparative religion classes of hinduism, islam and buddhism. There was sex ed, although I can't quite recall if family planning and protected sex were discussed. I think they may have been, since it was never controversial to hear about later on.
I still resent the mandatory RE classes though. Valuable time was wasted which could better have been spent on philosophy, maths, electronics, geology and all sorts of other potential electives that get overlooked.
I wonder if there are any private schools that are secular in nature, which attract good quality teachers and resources? That's the kind of stuff I'd pay for for any future kids I may have.
(Although I do agree, private schools should be privately funded - not gov't funded).