Teach the idiocy
You know what never works? Allowing those with no educational background or training whatsoever to dictate what kids should be learning. I know, it seems so foolproof.
Granted, I can't say the reverse is always true either; back in high school -- I won't speak its actual name for legal reasons, so let's just call it Schmoyola Jesuit High School, in Montreal -- for some reason, someone thought it would be a totally peachy keen idea to cut a class on sexuality to make room for a class called world religions. That actually doesn't sound like a complete waste, until you realize this class was used to point out why every other religion was wrong. I swear to god, I couldn't make that shit up if I tried. By the time I graduated, I couldn't tell you how effective condoms were for safe sex, but I could tell you why Buddhism was wrong. Thanks, Schmoyola!
The rather ironically named PEACE (Public Education Advocates for Christian Equity) is currently trying to get schools to send letters home to parents so that they can be warned when their kids might be taught sex education or anything involving non-heteronormative families. And there's currently another group, the Parental Rights in Education Defense Fund, dedicated to raising money for parents who try to sue school boards if they feel that the knowledge instilled in their children at school undermines their "religious freedoms" and "conscience rights."
Basically, it doesn't matter if what the school says is true: if the parents don't believe it's true, they should be allowed to sue. Yeah.
Personally, I think people are allowed to believe whatever they want. Whether your beliefs involve a bearded invisible sky giant or a lizard that lives in the sun or you think the entire world is just an autistic child's daydream, like the ending to St Elsewhere. Whatever, go right ahead. However, it becomes a problem when you start valuing the things you think are true over the things we know are true thanks to years of scientific study and research.
Furthermore, if you're willingly raising your children to ignore empirical evidence, that's fucked up. Part of being a responsible parent is encouraging your children to learn as much as possible in order for them to become proper functioning adults, and for them to realize that it's okay to admit they're wrong when new experiences and facts dictate otherwise. If you're deliberately trying to keep your children from learning, while simultaneously driving it into their heads that they're never wrong
. . . Well, if it's not full-fledged abuse, that's at least crappy parenting.
What I really have a problem with is this: if your religion encourages ignorance and misinformation, you should probably take some time to reflect on whether it's something worth believing in.
(Super cool comic from NatalieDee.com)