During the first half of the 20th century, Brazilian Protestants turned to their pens and periodicals to defend the legitimacy and beneficial nature of their presence in a majority Catholic nation. This period—spanning Brazil’s first republic, Getúlio Vargas’s authoritarian Estado novo, and the developmentalist era of Juscelino Kubitschek (1956–1961)—witnessed several regime changes and new national constitutions. Amid these political shifts, the Brazilian Catholic church sought to increase its cultural and symbolic dominance in the country. Meanwhile, several Brazilian Protestant groups came together to form the Confederação Evangélica do Brasil (CEB) in 1934, both to coordinate Protestant educational and social work and defend freedom of Protestant religious expression. With their denominational roots in Brazil extending less than one hundred years and their ties to US mission boards making them appear suspiciously foreign, Brazilian Protestants vehemently defended their patriotism. Relying on the writings of many CEB leaders, the organization’s periodical Unum corpus, and biannual reports, I argue that the Brazilian ecumenical leaders used several strategies to create a rhetorical defense of Brazilian Protestant legitimacy. They expressed occasional appreciation for Brazilian Catholics, celebrated Brazilian Protestant history and public recognition of contemporary Brazilian Protestants, and stridently opposed Catholic attempts to achieve cultural or social dominance. I also argue that because they maintained a constant defensive posture, the Brazilian Protestant ecumenists of the 1930s–1950s embraced a vision of ecumenism that explicitly excluded Roman Catholicism.