Try it. Ask someone what the government should do to restrict parents’ rights to send their kids to religious schools. Nine times out of ten, you’ll get the same answer: Nuthin. But if you ask if the government has a duty to protect kids from horrific abuse, most people will say yes. And as this week’s news headlines confirm, that contrast leads to our endless confusion about the proper relationship between religious schools, parents, kids, and government.

Whatever your religion, you don’t have a right to abuse your kids and call it “homeschooling.”

Exhibit A: The parents in the terrible Turpin case have been sentenced to life imprisonment. You may remember this horror-show case from last year. A family with a dozen kids was caught subjecting the kids to abuse—including starvation, sexual abuse, and neglect—under the guise of “homeschooling.”

Exhibit B: A New York judge has ruled that conservative religious schools do not have to comply with government orders. In this case, the city and state governments have been trying for a while to supervise the curriculum at some private Jewish schools. The accusation was that the religious schools had been teaching students only in Yiddish and Hebrew, neglecting their studies in English and science, and neglecting the education of girls as a whole.

Exhibit C: New York has also threatened to take away religious exemptions for measles vaccines. Lots of Orthodox Jewish families have abstained. Traditionally, they were given lots of wiggle room for religious claims. No longer.

…but do parents have a right to teach only in Yiddish? …or to skip vaccines?

What does all of this tell us about the proper relationship between government, family, and private schools? Just this: The dividing line is not really about religion. Rather, it is about abuse. Parents and religious communities generally have lots of leeway when it comes to their kids’ educations.

If and when a kid is being abused, however, or hurt physically, the government tends to feel justified in stepping in. This is true when the harm is done only to the religious kids themselves—as in the case of the Turpins or the Jewish-school students—or to the wider public—as with the unvaccinated students.

The problem, of course, is that “abuse” is often in the eye of the beholder. What the Turpins did to their children was an obvious case. But, as Lawrence Krauss has accused, are ALL young-earth creationists guilty of abusing their kids by teaching them zombie science? Or, remembering the case of NFL legend Adrian Peterson, what about parents and schools who use corporal punishment?

No one knows. We don’t have a clear and universal definition of “abuse” that we can apply in every situation. For secular people like me, the idea of neglecting topics such as English and science seems abusive. It seems to harm the life chances of students. For people like me, too, it seems abusive to teach kids–for religious reasons–that only heterosexuality can be practiced morally.

But there’s the rub. I know that plenty of parents disagree. They want their kids to learn young-earth creationism because they love their kids. They want their kids to learn the (alleged) dangers of LGBTQ sexuality because they love their kids. Can that be abuse?

No one knows.

In the end, the reason it is so hard to build a convincing wall of separation between church, state, and school is not because of Jesus or Jehovah or Jefferson. Rather, it is because no one has a simple, universal definition of “abuse.”