SALT LAKE CITY — Their faces contort as they consider the question, trying and failing to recall what memorable religious event happened 500 years ago. Most participants in Craig Harline's video are stumped about the details of the Reformation, even when he gives them a hint.

"Martin ," says Harline, a professor of history at Brigham Young University.

"Oh, Martin Luther King. He can't be that old. Oh, help me!" says one woman, falling into the same trap as many of the people interviewed.

In just under four minutes, Harline perfectly captures the confusion surrounding the 500th anniversary of the Reformation. While academics and faith leaders revel in the opportunity to talk and write about the global impact of Protestantism, many Americans are confused about what they're supposed to be commemorating.

"U.S. Protestants are not united about — and in some cases, are not even aware of — some of the controversies that were central to the historical schism between Protestantism and Catholicism," according to a recent survey on the Reformation from Pew Research Center.

The Reformation refers to a period of religious upheaval that began in 1517. Catholic monk Martin Luther, and then a number of other theologians after him, questioned the Catholic Church's spiritual authority, urging a return to the Bible. Their teachings resonated with the people and launched the Protestant movement, which spawned hundreds of new Christian denominations.

Although around two-thirds of U.S. adults can correctly identify the Reformation (65 percent) and Luther (67 percent) on multiple-choice questions, many of today's Protestants espouse different beliefs than the men who launched their faith groups, Pew reported.

More than half of Protestants (52 percent) say both good deeds and faith in God are needed to get into heaven, but Luther preached that faith alone (sola fide) led to salvation, the survey noted.

"'The ecumenism of amnesia' is a potential subhead for Pew's research," said Tal Howard, a professor of history and the humanities at Valparaiso University, at the Religion News Association's annual conference last month.

In Harline's video, produced with the help of BYU's Neal A. Maxwell Institute for Religious Scholarship, participants struggle to explain the theology behind indulgences, which helped prompt Luther's rebellion against Catholic authorities. Medieval Catholics could purchase indulgences in order to save deceased loved ones from punishment in purgatory.

"Do you have any idea what an indulgence is?" Harline asks.

"Yeah, I do that every single Saturday with ice cream," says one young woman, who was filmed on the BYU campus.

Exasperated by all she doesn't know about religious history, another woman suggests a new line of questioning.

"Ask me anything you want about the Dallas Cowboys. I can tell you," she says.

Public misunderstanding and even disinterest are facts of life for professors who specialize in the Reformation, said Alec Ryrie, author of "Protestants: The Faith that Made the Modern World." The key is developing a good sense of humor.

"I think the best reaction I had was from somebody who saw online that I had a book coming out called 'Protestants' and didn't know what the word was. They read it as 'Protest Ants' and did a little picture of ants marching and carrying placards," he said.

Ryrie added, "I kind of like that, but I'm afraid that's not what the book is about."

How to learn more

Time is running out to brush up on Reformation facts before the official 500th anniversary on Oct. 31, but there are a variety of resources available for aspiring Protestant scholars.

BYU's Maxwell Institute, which sponsored a Reformation conference last month, has uploaded lectures on this religious event to its podcast channel. Simply search "Maxwell Institute Podcast" through iTunes or visit the organization's YouTube page.

Dozens of new Reformation books have been published in time for this year's festivities. Check your local library for Ryrie's "Protestants," Harline's "A World Ablaze: The Rise of Martin Luther and the Birth of the Reformation" and other recent research.

PBS released a new Reformation documentary, "Martin Luther: The Idea that Changed the World," in September. Check your local PBS schedule for showings.

Throughout October, Religion News Service will be publishing articles on the Reformation by Emily McFarlan Miller, who took a pilgrimage to Luther's homeland this summer. Follow the series on its website.

The Deseret News will also provide ongoing coverage of the Reformation's lessons for the contemporary world. Here are the articles that have already been published:

5 lessons from the 'Martin Luther: Art and the Reformation' exhibit

How the Reformation changed Easter

Why the myth of the Protestant work ethic won't die