This book is the founder of the prolific field of eocnomic sociology. It introduces the concept that culture (in the form of the protestant ethic) is better adapted to fit capitalism. Therefore, capitalist growth was found more frequently in protestant societies than in others.
Rather than a general theory or explanation of either economics or religion, Weber attempts to draw a specific link between what he sees as the conjunction of the work ethic of Protestant (mainly Calvinist) spiritual teachings, and the success of Western European Capitalism.
This book is legendary. Max Weber arguably was the first social scientists who devoted his life's work to cross-cultural studies. His pioneering study of "The Protestant Ethic and the Spirit of Capitalism" combines a broad, almost universal, vision of human desires and ideas with painstaking details of how certain religious movements transformed the economic basis of feudal Europe, and later the United States, into an economy of competition and free enterprise.
"The Protestant Ethic" is by far the most famous sociological study and is unsurpassed in theoretical boldness and creativity.