The Profits of Religion: An Essay in Economic Interpretation is a nonfiction book, first published in 1917, by the American novelist and muck-raking 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.”