“What we heard was not new; it was a new low,” Dr. Warnock said. “I had to wrestle with how do I characterize what he said without saying it.”

What emerged was a service that swerved between the past and the present, a renewed political reckoning and another denunciation of the president from one of the country’s most prominent black churches. Before a rapt crowd that included Dr. King’s only surviving sibling, Dr. Warnock accused Mr. Trump of trafficking in “hate speech” and described him as “willfully ignorant, racist, xenophobic.”

“I don’t know that he’s listening, and I don’t know that it matters,” Dr. Warnock said in an interview. “Even if Trump were to leave tomorrow, we still have to deal with the large segment of white evangelicals who voted for Trump. My battle is not so much with Trump as it is with Trumpism.”

Mr. Tucker said that perhaps the progress the civil rights movement had fought for had missed parts of the country. Maybe black progress had engendered more resistance than he had understood.

“We moved beyond a point, but we didn’t carry the country with us,” he said. Today he hears white people complain that their problems have been forgotten as political leaders focus on black misery. “White people are saying that what has happened is you took equality from some white people and gave it to black people,” he said. “That’s where we are right now, I think.”

Some say that Mr. Trump’s language is distracting from an important policy question that will affect millions of people. But church leaders said that made his remarks all the more inexcusable. Words matter all the more, they said, when they come from the mouth of the president.