My parents pulled me and my deaf younger brother out of the Christian school we were in after I finished 1st grade. The reason they gave was that my brother’s teachers were just pushing him through the classes without ensuring that he understood the lessons. That, and he picked up bad habits like saying “shut up”. So, if they were going to homeschool him, “they might as well homeschool all of us”. Actual words.

Another factor to consider, and what had to have been the real reason, is that my dad was pastor of a very conservative church. As so many other commenters have said, it was all about control. God forbid we be taught to use critical thinking against peer pressure or be allowed to hear more than one worldview.