In the decades after World War II, Protestant missionaries abroad were a topic of vigorous public debate. From religious periodicals and Sunday sermons to novels and anthropological monographs, public conversations about missionaries followed a powerful yet paradoxical line of reasoning, namely that people abroad needed greater autonomy from U.S. power and that Americans could best tell others how to use their freedom. In The Gospel of Freedom and Power, Sarah E. Ruble traces and analyzes these public discussions about what it meant for Americans abroad to be good world citizens,...