“Place the lives of children in their formative years, despite the convictions of their parents, under the intimate control of experts appointed by the state, force them to attend schools where the higher aspirations of humanity are crushed out, and where the mind is filled with the materialism of the day, and it is difficult to see how even the remnants of liberty can subsist.”

A very astute in the obvious observation. The occupying statist theocracy infesting this land's religious seminaries (government schools) have trained up the next generation of parents to not be able to even recognize any remnants of liberty.

Yes an accurate observation, but, Machen lacked the backbone to mix religion and politics, perhaps at his lack of understanding three key liberties. The first, Chophshiy, economic liberty would cut against the grain and the governments "legalized plunder" of the sovereign individual. Sounds very much like the denominational stance for socialism that infest this nation and global communities at large. One star for the correct observation.

Wouldn't it be best to place the children in the most natural environment?  Wouldn't it be best to question every procedure of the child's rearing, administering, and preparation?

The subsistence of the remnants of liberty is unfortunately miniscule today, much in part due to compulsory government schooling. 

Today, few Americans truly value Liberty and understand the price of upholding it. Dependency and a sense of victimhood are central themes in today's education, especially in inner cities. Here, maintaining poverty among the poor serves as a lucrative scheme for politicians who enrich themselves through their positions and influence-peddling. It's the second oldest trick in the book, bearing a striking resemblance to the first.