Unveiling the Beast tells the untold history of how a movement of American Protestants mounted one of the most provocative challenges to the Christian nationalist ideology that drove U.S. imperialistic policies at the turn of the twentieth century. Told through the lens of an American-born apocalyptic tradition known as Seventh-day Adventism, this account introduces a new cast of anti-imperialists. It shows how they developed a theological and historical framework to protest the politicized religious establishment that endorsed the government’s abuse of power. They spearheaded one of the leading campaigns of Christians against the Christian Lobby and made the case that the Christian nationalism influencing U.S. domestic policy was also at the heart of American imperial ambitions abroad. Adventists articulated a prophetic warning: imperialistic policies that violated human rights abroad would set a precedent for a more centralized government that would infringe on the rights of U.S. citizens at home.