This essay discusses the domestic moral and cultural reformism and the liberal expansionist discourses of leading Japanese Protestant journalists at the turn of the 20th century. It gives special attention to Uchimura Kanzō and examines his important theoretical relationships with the leading proponents of imperialism at the time, such as Tokutomi Sohō, Yamaji Aizan, and Takekoshi Yosaburō. Although it is important to consider Uchimura’s religiosity and intellectual biography because they are essential to his resistance to imperial Japan, it is also necessary to compare Uchimura’s journalistic writings with those of his friends and contemporary rivals and consider them together in the context of the intellectual currents of the time. As I argue, amid developing imperialism in East Asia at the turn of the 20th century, Protestant intellectuals overall championed cosmopolitanism, promoted liberal education and international comity and ethics over jingoism, and urged sophisticated cultural development comparable to that of the West. Uchimura and other Protestants, moreover, supported liberal expansionism, that is, Japan’s expansion through peaceful and economic means in tandem with British and American imperialism and emigration overseas. Furthermore, liberal expansionism was inspired by a historicist view that the development and expansion of liberalism and capitalism would inevitably lead Japan and the rest of the world to peaceful coexistence and higher moral civilization.