This dissertation examines the life and work of Charles Ewing Brown (1883-1971), an influential twentieth-century leader of the Church of God (Anderson, IN). During his editorship of the Gospel Trumpet from 1930 to 1951, Brown reinterpreted Christian doctrine in ways that often challenged predominant evangelical and fundamentalist theologies of the mid-twentieth century. Although often associated with theological developments in the nineteenth century, the holiness movement impacted the twentieth century in significant ways, concurrent with the contributions of pentecostalism and neo-evangelicalism. In the late 1950s, a prominent mainline leader heralded the rise of the “Third Force in Christendom,” which prioritized an experiential and primitivist faith that was not encapsulated in Roman Catholicism or historical Protestantism. Despite the presence of holiness groups like the Church of God in the Third Force, prevailing historical narratives of the mid-twentieth century have prioritized the importance of the Reformed fundamentalist tradition associated with Baptists and Presbyterians. In contrast, Brown’s holiness fundamentalism rejected the premillennialism and cultural separatism that prevail in most historians’ depiction of the tradition. Overall, Brown complicates how historians have understood terms such as fundamentalist and evangelical. This work offers a nuanced historical account by showing how a significant holiness leader inherited and modified the beliefs and practices of formative traditions. Through a survey of monographs, editorials, and addresses, this dissertation foregrounds the foundations and implications of Brown’s claim of being an evangelical and a fundamentalist. It begins with a biographical chapter and successive chapters explore how Brown’s outlook informed his view of revivalism and doctrine, his ecclesiology, his critique of premillennialism, his articulation of the social dimensions of Christianity, and his socio-political commentary. The conclusion contextualizes Brown and analyzes his historiographical significance. For Brown, the evangelical and fundamentalist disposition was primarily communal, and the prevailing trend toward hyper-individualism and separation deeply concerned him. By challenging the assumptions about the conservative nature of evangelicalism and the epistemological foundation of fundamentalism, this study offers an initial foray into how holiness groups shaped the contours of twentieth-century American Christianity. It reveals Brown’s continuity with nineteenth-century evangelical social reform efforts and with late twentieth-century progressive evangelicals.