Jesus instructed his followers to "love your enemies, do good to those who hate you, bless those who curse you, pray for those who mistreat you" (Luke 6:27-28). Not only has this theme long been among the Church's most oft-repeated messages, but in everything from sermons to articles in the Catholic press, it has been consistently emphasized that the commandment extends to all humanity. Yet, on numerous occasions in the twentieth century, Catholics have established alliances with nationalist groups promoting ethnic exclusivity, anti-Semitism, and the use of any means necessary in an imagined...