(Johann) Wilhelm Herrmann (1846—1922) was a German Liberal Christian theologian. As a student, the Conservative Christian and Anti-Modernist theologian John Gresham Machen studied with him in 1905. Other students included Karl Barth and Rudolf Bultmann. In his day Herrmann was famous throughout the Western World's Academy, even being invited to lecture at the University of Chicago in 1904. His book The Communion of the Christian with God (1886 German, 1896 English) went through seven editions and was widely read throughout the Academy (American, British, and European). The book was about how to pray and commune with God when dealing with the 19th century mechanical scientific worldview. According to Herrman, prayer could be achieved through personal Christianity and an encounter with Jesus, the living God. 
What makes Hermann liberal
The problem with Herrmann's thesis—the reason why both Machen and Barth rejected his theology—is that it ignores most of the first 500 years of the Christian Church as well as 16th century Protestant Reformation Christian doctrines. Such overlooked doctrines include the doctrine of Creation, the doctrine of Incarnation, and doctrine of Eternal Life among others.
- The Communion of the Christian with God (1906 English Edition, found on Internet Archive)
- The Communion of the Christian with God (1895 English Edition, found on Google book search project)