This work first examines the theological streams of influence that constitute Brethren theology—Anabaptism and Radical Pietism—with particular focus given to key thinkers and leaders. It then explores the nuances of what came to be American Fundamentalism and Protestant Liberalism of the late nineteenth and early twentieth centuries, which provide important context to the thought of J. Allen Miller (1866–1935), a central Ashland Brethren theologian of that period. Miller’s theology demonstrates sympathy with both poles of the theological spectrum but remains distinct as a thoughtful mediation between these two extremes. Miller’s theological approach, termed “Word-Spirit Communal Revelationalism,” consists in his particular theological epistemology and biblical hermeneutics. When Miller’s theological witness moves into conversation with American evangelicalism, it proves helpful for the Ashland Brethren as they engage with the contemporary American evangelical landscape. His witness assists Brethren and other American evangelicals in offering a corrective to several pathologies or distortions identified within American evangelicalism. His theological method assists the larger American evangelical movement with tools for mediation over against polarization.