Allan MacRae, one of the original faculty members to join J. Gresham Machen at Westminster Theological Seminary, once observed, “All through the history of the church of Christ there has been a ceaseless struggle to maintain the truth.” That perennial struggle took a rather virulent form from 1890 through the 1930s.

The promise of a new century fostered a progressive spirit and an unfettered belief in the goodness and potential accomplishment of man. World War I offered a massive setback, especially in Europe. America, however, being an ocean away and untouched by war directly, ran headlong into the 1920s. “The Roaring Twenties,” they would call it. The description for this greater period is modernism. The rejection of God and the dismissal of religion sit atop the list of modernism’s endeavors. This cultural bomb landed hard on the American church.

As modernists left the church and modernism left God behind, church leaders across denominations began to “rethink” their theological convictions and their ministerial priorities. They were not willing to be left out of the cultural conversation, resulting in what church historians call liberalism. Liberalism accommodates modernist sensibilities, primarily summed up in an aversion to the supernatural and a godlike belief in human goodness and potential. This means that the doctrines of Scripture as inerrant and authoritative will be passed over. This means that God will be reduced to a God of love and acceptance. This means that Christ will be reduced to a good man or to a brilliant teacher. This means that the cross will be reduced to an example of love and selflessness. This means that the future kingdom of God will be transferred to a utopian society of equity here on earth. The cumulative effect of these doctrinal departures was that the church became derelict in its commission, ceasing to be light in the darkness.

As MacRae’s quote reminds us, however, there are those who enter the struggle to defend the truth. In those early decades of the 1900s, they were called fundamentalists. The word fundamentalist was first used to describe anyone who believed in the fundamentals of the faith and also fought for them. The fundamentals included the inerrancy of Scripture, the deity of Christ, His substitutionary atonement on the cross, miracles, and the necessity of preaching and believing in the gospel. To understand this divide between fundamentalism and liberalism, consider three individuals: Charles Augustus Briggs (1841–1913), Harry Emerson Fosdick (1878–1969), and J. Gresham Machen (1881–1937).

Briggs studied at Union Theological Seminary in New York (a seminary of the Presbyterian Church in the United States of America or PCUSA) and would later study abroad in Germany. Briggs fully embraced higher-critical theory, a view that essentially denies the divine origin of the Bible and subjects it to the same scrutiny that any other text would receive. Billy Sunday used to quip in his evangelistic crusades: “Turn hell upside down and what’s stamped on the bottom? ‘Made in Germany.’ ” When Sunday said that, he had higher criticism—and its direct impact on American scholars such as Briggs—in mind. Throughout the 1880s, Briggs skirmished with the conservatives, especially the faculty at Princeton Theological Seminary. In his 1891 inaugural lecture as the Edward Robinson Chair of Biblical Theology at Union, Briggs fired a cannon volley. The lecture, titled “The Authority of Holy Scripture,” made the claim that the dogma of verbal inspiration is a “barrier” to a proper understanding of God’s Word. Briggs was charged with heresy and found guilty in 1893, which forced Union Seminary to fire him. Union quickly rehired him through an independent funding venue. The proverbial hole was punctured in the dike. Union became the headquarters of liberalism in the Presbyterian and even American church, and biblical scholarship in many universities and seminaries was soon flooded with heretical views of the Bible—and the orthodox views on all doctrines began to be swept away.

Dietrich Bonhoeffer spent 1929–30 studying at Union and found it abysmal. He found churches across New York City equally abysmal. After visiting church after church, including Fosdick’s, he briefly noted in his report home, “No theology here.” What he really meant was that all he heard from pulpits was the word of man, not the Word of God. Higher criticism had gone from Germany to the American academy to the American church. Ideas, indeed, have consequences. If Briggs illustrates liberalism’s impact on the academy, Fosdick illustrates liberalism’s impact on the church. Two things propelled Fosdick into the limelight: he was captivating and charismatic, and he had the backing of America’s richest man, John D. Rockefeller.

On May 21, 1922, Fosdick preached the sermon “Shall the Fundamentalists Win?” in which he rethought the Christian faith “clear through in modern terms.” It was textbook accommodation. Take, for instance, his view of the virgin birth of Christ. Fundamentalists, Fosdick opined, say that we should understand the virgin birth as historical fact and as literally and undeniably true. Fosdick countered, “To believe the virgin birth as an explanation of great personality is one of the familiar ways in which the ancient world was accustomed to account for unusual superiority.” He proceeded to mention the Buddha and Zoroaster as having the same such birth. Yet to deny the virgin birth is to deny the deity of Christ, and that is to deny the orthodox gospel. H. Richard Niebuhr would come to describe liberalism as teaching that “a God without wrath brought men without sin into a kingdom without judgment through the ministrations of a Christ without a cross.” That was Fosdick.

Into this fray came J. Gresham Machen. Machen was the son of a Baltimore attorney, and his mother (née Gresham) was from Macon, Ga. He studied classics at Johns Hopkins and then pursued master’s degrees at both Princeton University and Princeton Theological Seminary. Then he headed to Germany for further study. He returned to Princeton Seminary, where he served as a professor from 1906 to 1929, interrupted by two years of service with the YMCA in France during World War I. He was mentored by the “Lion of Prince­ton,” Benjamin Breckinridge Warfield. When Warfield died in 1921, the mantle of defender of the faith fell to Machen.

Machen had earned his credentials, had faced German higher criticism directly, and possessed a keen mind. He loved orthodox doctrine, the supernatural, and the gospel. All that came to bear on the book he published in 1923, Christianity and Liberalism. The book walks through the essential doctrines of Christianity, showing that liberalism is not a new version of Christianity but a false gospel altogether. Consequently, liberalism holds out no hope. It offers stones instead of bread.

Machen’s book was hated by theological liberals and scathed by them in reviews. Curiously enough, the intellectual moderns, such as Walter Lippmann and H.L. Mencken, respected the book and recognized the validity of Machen’s arguments. For fundamentalists, the book added steel to their spine as they continued the fight for the faith. But what happened to Machen after his book?

In 1929, Princeton Theological Seminary reorganized the board and took a turn directly toward liberalism, effectively forcing Machen out. He crossed the Delaware River and opened Westminster Theological Seminary in Philadelphia. When Machen organized a new mission board because the denomination’s mission board had shifted the focus from gospel proclamation to social transformation, he was defrocked. In 1936, he led in the formation of the Orthodox Presbyterian Church. A few months later, on January 1, 1937, Machen died of pneumonia in North Dakota, where he had traveled to smooth troubled waters in a church in the new denomination.

Machen’s first biographer and colleague, Ned Stonehouse, called him “Valiant for Truth,” after John Bunyan’s courageous character. That he was. There was a timeliness to Machen’s book and his fight. But there is also a significant timelessness. Consequently, Christianity and Liberalism may be even more applicable today, one hundred years after it was first published, than it was originally. As we contend for the faith in the perennial, ceaseless struggle as it manifests in our day, we can give thanks to God for Machen and his book, and we would do well to spend some time in its pages.