Most home-schooling is of a religious nature. Home-schooling is for fundamentalist Christians (for the most part) a means of indoctrination, not education. What especially curls the hair of the fundies is the belief that Evolution is a valid method of understanding the history of the earth and its creatures.
Home-schoolers believe the Bible. Anything they deem contrary to the Bible must, ipso facto, be false!
In many states, a form of Creationism is being taught, often called Intelligent Design. This, in spite of the fact that the courts have struck down such teaching as religion is disguise! Nowhere is this misguided teaching more prevalent than in the Lone Star State. The majority of the Texas Board of Education are fundamentalist Christians who care little for education but are intent on indoctrinating young Texans in the mythologies and legends of the Bible. Thus Texas children are taught the earth is 6,000 years old, that humans walked with dinosaurs, that Adam and Eve were real people, etc.
And this is a cause for lament as well as legal action. The youth of Texas are heading into a world ill-prepared to compete because they lack fundamental knowledge of the nature of life and how life has evolved through literally millions of years!