This study presents a historical and theological defense of the original meaning of 'fundamentalism' as a commitment to core Christian doctrines—such as biblical inerrancy, the virgin birth, substitutionary atonement, bodily resurrection, and the reality of miracles—emerging in response to 19th- and early 20th-century challenges from liberal theology, Darwinian evolution, and the social gospel. It traces the movement's origins to the 1910–1915 'Fundamentals' series, which sought to preserve orthodox faith amid rising skepticism, while highlighting how the term became tarnished by the Scopes Trial and later co-opted by cultural caricatures. The preacher warns against modernist tendencies in contemporary Christianity, including moralistic preaching, cafeteria-style belief, and the rise of 'moral therapeutic deism,' which reduce faith to ethical behavior and personal well-being rather than doctrinal truth. Ultimately, the sermon calls the congregation to reclaim the original, biblically grounded meaning of fundamentalism—not as rigid dogmatism, but as a faithful, intellectually engaged, and theologically robust commitment to the gospel, urging believers to reject both intellectual arrogance and anti-intellectualism in favor of a balanced orthodoxy and orthopraxy.