The Discovery Channel aired "Selling Murder: The Killing Films of the Third Reich," a documentary on films found in archives after German reunification. The Nazis had a public relations problem: they wanted to exterminate weaker members of society, but Lutheran Germany had a history of compassion toward the old, infirm, and the mentally ill. In order to change public perception, the Nazis hired some of Germany's best filmmakers.

I watched the Nazi films with chilled fascination. Certain qualities—the narrator's "objective scientist" voice, the soothing, classical soundtrack, the follow-the-dot reasoning—reminded me of a fifth-grade science film. A hunter strides through the Black Forest. "Nature runs by fixed laws," says the narrator. "The fox catches the weak rabbit, and the hunter shoots the weak deer."

Any realities that challenged the film's message—Don't hunters go after strong deer with big racks?—were glossed over. This was Nazi propaganda, not pure science. Next the film showed patients at Hadamar, a facility for the mentally disturbed. Klieg lights aimed at unnatural angles made the patients look ominous, their faces angular and deeply shadowed, their eyes wild.

Shift to a bureaucrat displaying budget graphs. It takes 100,000 Deutschmarks to keep one of these defectives alive, he explains—money badly needed by the Fatherland. We should follow the example of nature and allow the weak to die….

"Selling Murder" ended with a surprising twist. Despite their slick films and other attempts to sway public opinion, the Nazis failed to exterminate the physically and mentally disabled. Jews, Gypsies, and homosexuals they murdered virtually without protest; the disabled, they had to let live.

Why? The change in Nazi policy traces back to one brave woman, a Christian nurse who worked at Hadamar. When the facility was converted into a gas chamber, she could not keep silent. She documented the facts and reported them to her bishop, who released them to the public. The resulting outcry from the church forced the Nazis to back down. Perhaps her courage can serve as a prophetic model for Christians today.