I first read that one in a Duck U political science class in 1967 or so.  I especially liked the idea that the "True Believer" can easily move from one type of movement to another which would appear to be antithetical to each other.

Hoffer's theories do account for some attitudes I see on this site.  

http://www.religionofbusiness.com/books/1-page-summary-the-true-believer-by-eric-hoffer