No leaders in the evangelical movement said they could see any clear signs of an organized resistance to Mr. Trump rising from the editorial. And even dissenters like Mr. Wehner acknowledge they are vastly outnumbered.

According to a recent poll from the Public Religion Research Institute, 77 percent of white evangelical Protestants approves of the job Mr. Trump is doing in office, including half who strongly approves. And nearly all — 98 percent — of Republican white evangelical Protestants said they opposed Mr. Trump’s impeachment, the institute found.

In 2016, 81 percent of them voted for Mr. Trump over Hillary Clinton, most likely helping him carry states like Florida and Michigan, which allowed him to win the Electoral College despite losing the popular vote. The Trump campaign is putting an intense focus on turning them out to vote next year, with groups like Mr. Reed’s Faith and Freedom Coalition pledging to raise millions of dollars and deploy tens of thousands of volunteers on his behalf.

Many young evangelicals, however, are more socially liberal on issues like same-sex marriage and troubled by Trump administration policies like separating migrant families at the border and denying climate change.

Mr. Galli appeared to reach out to future generations of evangelicals when he wrote, “If we don’t reverse course now, will anyone take anything we say about justice and righteousness with any seriousness for decades to come?”

The reaction to the editorial, while perhaps not signaling the beginning of a wave of defections among white evangelicals, could be another sign that the middle is disappearing in American Christianity, just as it is in politics. It was also a reminder that the upcoming presidential election would be a test not only of Mr. Trump’s political strength, but also of the future of the faith that abetted his rise.

Evangelicals who are troubled by the president’s conduct said they feared that he had done long-term damage to their cause, and that the lack of pushback had only hurt them more, especially with young people. Peggy Wehmeyer, a journalist based in Dallas who writes often about her faith, said she heard a lot of “Thank God Mark Galli said this,” among her friends.