Piety or Pieteism
Pietism as used here includes two things. First, the limitation of piety to the personal or internal, often equated with the "spiritual." The "outer" world, the world of art and music and politics and science and education and technology and economics, is usually considered under Satanic control. In any case, to concern oneself with these matters in a distinctly Christian way is to divert attention from the truly "spiritual" issues of life.
Second, pietism usually involves substituting man's command for God's (see Mark 7). This is its most pernicious trait. Pietists are convinced the Bible's ethics are insufficient, so they must add their own list of regulations that they impose on others: prohibition of watching movies, smoking cigars, employing birth control, driving a Mercedes, drinking coffee, playing the ponies, and so on. "Courtship" is moral and dating is not; at-home moms are moral and working moms are not; dresses are moral and pantsuits are not; and on and on.
My guess (or hope) is that the great Pietist theologians did not endorse this "pietism" - especially the second part. If some find Sandlin's description objectionable, keep in mind that the word "puritan" has been abused to far greater degree.
Whatever the word we use, the traits Sandlin describes make for bad religion and worse ethics - yet "pietistic" Christianity is how most Americans conceive the faith. And this pietism accounts for nearly all of the insufferable and annoying traits of the American character. If there is to be reformation and revival in American Christianity, a lot of it would be a purging of these pietistic ideas.