This show, “Hitler and the Germans: Nation and Crime,” opened Friday. It was billed as the first in Germany since the end of World War II to focus exclusively on Adolf Hitler. Germany outlaws public displays of some Nazi symbols, and the curators took care to avoid showing items that appeared to glorify Hitler. His uniforms, for example, remained in storage.

Instead, the show focuses on the society that nurtured and empowered him. It is not the first time historians have argued that Hitler did not corral the Germans as much as the Germans elevated Hitler. But one curator said the message was arguably more vital for Germany now than at any time in the past six decades, as rising nationalism, more open hostility to immigrants and a generational disconnect from the events of the Nazi era have older Germans concerned about repeating the past.

“The only hope for stopping extremists is to isolate them from society so that they are separated, so they do not have a relationship with the bourgeoisie and the other classes,” Mr. Thamer said. “The Nazis were members of high society. This was the dangerous moment.

“This we have to avoid from happening.”

Increasingly, Germans have put the guilt of the past behind them, reasserting their pride in national identity in many positive ways. But there also have been troubling signs seeping from the margins into the mainstream.