Francis A Schaeffer is very well known. He was ahead of his time. My husband read his material in college in the 70’s. He definitely spoke and wrote of the times we are living in now.
http://en.wikipedia.org/wiki/He_Is_There_and_He_Is_Not_Silent
One of Schaeffer’s books is assigned for a religion class my son has this semester at Hampden Sydney College in VA. Francis Schaeffer is a magna cum laude graduate of HS-C class of 1935.