The argument Machen makes powerfully in Christianity and Liberalism is that liberals in the 1920s had abandoned the Christian religion—that though liberal Protestantism tried to go by the name Christian, it was actually an entirely separate religion. He makes this case methodically throughout the book, contrasting the two religions with regard to doctrine, God and man, the Bible, Jesus, salvation, and the Church. Each topic gets a chapter, and in each, Machen demonstrates that “at every point the two movements are in direct opposition.”

On March 17, 2015, the Presbyterian Church (U.S.A.) gave its official approval to same-sex marriage. The Episcopal Church gave its approval that summer. As conservative congregations today leave the United Methodist Church, that denomination is now also falling in line.

One hundred years ago, most Americans would have been astonished that the country’s powerful Protestant denominations would one day enthusiastically embrace such sin. But J. Gresham Machen likely would not have been surprised. In fact, Machen, a professor at Princeton Theological Seminary in the early 20th century, was among those who saw this—or something very like it—coming.

This year marks the 100th anniversary of the publishing of Christianity and Liberalism, Machen’s ringing defense of the historicity and doctrines of Christianity. Westminster Seminary Press has published a 100th anniversary edition of the book, with a foreword by Kevin DeYoung. Ligonier Ministries also published an anniversary edition. And because of the book’s historic importance and continuing significance today, it is WORLD’s 2023 Book of the Year.

If you want to explore the background of the moral ­collapse in churches today over same-sex marriage and other LGBTQ issues, this book is a good place to start. That collapse follows logically from the more important and foundational fight of 100 years ago.

The argument Machen makes powerfully in Christianity and Liberalism is that liberals in the 1920s had abandoned the Christian religion—that though liberal Protestantism tried to go by the name Christian, it was actually an entirely separate religion.

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