A century ago, a new, “modernist” liberal theology was infiltrating Protestant seminaries throughout the United States, transported primarily from Germany. J. Gresham Machen, an opponent of this new liberal theology, wrote a volume entitled Christianity and Liberalism in which he argued that historic Christianity and “modernist” theology were incompatible systems. To Bible-believing Christians like Machen, certain “fundamentals” were non-negotiable for authentic Christianity, such as the inspiration of Scripture, the deity and virgin birth of Jesus, the substitutionary atonement, the bodily resurrection of Jesus, and the literal Second Coming.