The Profits of Religion - Upton Sinclair

"The Profits of Religion: An Essay in Economic Interpretation" is a non-fiction book, first published in 1917, by the American novelist and muckraking journalist Upton Sinclair. It is a snapshot of the religious movements in the U.S. before its entry into World War I. In this book, Sinclair attacks institutionalized religion as a "source of income to parasites, and the natural ally of every form of oppression and exploitation." (Summary from Wikipedia)