In this book Ernst Troeltsch touches on the contrast between Protestantism and Catholicism, as well as Protestantism in relation to historical developments in politics, economics, social life, science, art, and feeling. Ernst argues that the early Protestantism of Luther and Calvin was not radical, but reform-minded, retaining and having many things in common with the "Church-civilization" of Catholicism. Today, he says, modern Protestantism is, though related to early Protestantism, not properly its progeny, but a combination of sectarian, Anabaptist, and radical groups; and, whatever resemblance or claim it may make to early Protestantism, this, in many respects, can only be granted in an indirect and unintentional way.