During the 1970s and '80s, the flocks gathered in conservative Protestant pews kept growing and growing -- until a third of the U.S. population could be defined as "evangelical."

Times were already getting tough for leaders of progressive Mainline churches, with sharp declines in budgets and worship attendance. But the waters were smooth for evangelicals.

"One might be considered a capable kayaker if the river currents are moving along at only a few miles per hour," said theologian David Dockery, during the recent convocation rites at Southwestern Baptist Theological Seminary in Ft. Worth, Texas, after he was inaugurated as its 10th president.

But the currents changed, while many contented evangelical leaders didn't spot the dangerous waves around them. "I fear that the waters of our cultural context have become much choppier and are moving evermore rapidly with each passing year," said Dockery, who noted that he was beginning his 40th year working in Christian higher education.

Consider a sobering new study -- "The Great Dechurching. Who's Leaving, Why Are They Going, and What Will It Take to Bring Them Back" -- by researchers Jim Davis, Michel Graham and Ryan Burge. Their numbers indicate that evangelicalism has backslid to where it was 50 years ago.

The big question is, "Why?" Dockery said he accepts the study's thesis that many boom-era evangelicals lacked "deep roots in their understanding of the Christian faith." Many evangelicals failed to teach practical discipleship in daily life and seemed reluctant to defend the truths "delivered to the saints" through the ages. This fear of theology has proven to be a disaster as America "has become more secularized, polarized and confused," he said.

Thus, the "Dechurching" trend leads straight to hard questions about seminaries, noted Burge, in his "Graphs about Religion" newsletter. He teaches political science at Eastern Illinois University and is one of my GetReligion.org colleagues.

Seminaries help define religious denominations and are "an incredibly important part of the religious economy. In many ways they are the canary in the coal mine for the health of American religion," he wrote. "If a tradition is training up a bunch of seminarians, one has to assume that it's because there is demand there. If their enrollments are declining, that's because things aren't going well."

For example, all six Southern Baptist seminaries made the Association of Theological Schools list of America's top 10 largest seminaries. Only two schools representing the old "mainline" are in the top 25. The other 23, are doctrinally "evangelical."

Signs of evangelical struggle are important. However, Burge also noted recent statistics showing that, while there are 60 million-plus U.S. Catholics, there are only 4,700 priests in training. All of America's Mainline denominations -- combined -- had only 6,461 seminarians in 2022. The Southern Baptist Convention has just over 13 million members, but 7,400 seminarians.

Southwestern is an important case study, in part because it was once the world's largest seminary. Now, it is the fifth largest SBC seminary and has, in the past two decades, faced a $140 million cumulative deficit. Each of the four presidents preceding Dockery were forced out due to a variety of conflicts about finances, ethics, falling enrollments or Southern Baptist infighting.

Dockery listed many educational challenges, including the need to "cross all generational, social, ethnic and economic boundaries." The seminary's goals and beliefs must be consistent, "whether in classes taught in English or Spanish, Mandarin or Korean, Portuguese or German, whether in classes taught on this campus, online, synchronous, asynchronous, hybrid -- however they be delivered for undergraduates, graduates or doctoral studies," he said.

Looming in the background, he said, is a larger issue -- that many believers now "hear the term 'theology' and think, 'That's something scary, or technical or abstract.' I'm aware that some even think that theology is irrelevant to our walk with God or that it creates a distraction from authentic practical ministry."

The key, he said, is that Southwestern will reject all claims that wrestling with trends in the modern world will require its faculty to abandon 2,000 years of Christian faith and teaching.

"There are certainly areas of theology which are debatable," said Dockery. "But to deny the teachings found in the pattern of Christian truth, as has sadly been done in almost every era of the Christian history, must be recognized as heterodox, or heretical."