The key thing for parents to accept is that we are our children's primary educators, whether they are homeschooled, in Christian school or in public school, and my own children have been in all three at various times. As parents, we are not off the hook just because we put our children in Christian school or homeschool, using Christian textbooks. Why not? Because they typically follow a sacred/secular approach instead of teaching how to develop a comprehensive worldview.
This is a problem right up to the university level. A Lutheran scholar, Robert Benne, did a study finding that the vast majority of Christian colleges teach what he calls an "add-on" approach. By that he means that the content of the courses is essentially what you would get in any secular university, with Christianity added on the side, in chapel and prayer groups. At one major Christian university, more than half the faculty said they would not even know how to give a biblical perspective on the subject they teach.
Read the whole interview.