The Crusades, when Christians tried for two centuries to oust Muslims from the Holy Land, left more than a million dead, with territory lost and gained and lost again -- all in the name of Jesus.
These days, Christians are not so quick to call the Crusades the golden age of Christendom, but a millennium later, their memory still reverberates.
Even so, Rodney Stark, 75, a professor of social sciences at Baylor University, says the crusaders were not all that bad, and certainly not barbaric, greedy warmongers.
In his new book God's Battalions: The Case for the Crusades, the 1996 nominee for the Pulitzer Prize depicts soldiers who truly believed their military service under God would cover over a multitude of sins -- namely all that murdering and marauding required of them in the tumultuous Middle Ages.
"I get tired of people apologizing for the Crusades, like Christians were a bunch of dirty looters that went over there and killed everybody," Stark said. "It just wasn't true."
Of course, apologies on the subject have been many. Pope John Paul II expressed regret for the medieval violence in 2000, the same year Wheaton College, alma mater of preacher Billy Graham -- who made evangelistic "crusades" famous -- changed their mascot from the Crusaders to the Thunder.
Stark argues that Muslims asked for it, that the Crusades were the first military response to Muslim terrorists and their looming, advancing Islamic empire. "It wasn't like they were harmless, little people minding their own business and tending their sheep," Stark said.
Indeed, Islamic powers were mighty before the Crusades and bounced back after Christian attempts at conquest ultimately failed.
"I suspect that Muslims will hate the book, and I'm sorry about that," Stark said. "That's just the way the world is. I make no apologies or real accusations."
Stark, a sociologist of religion, concedes he is no historian of the brutal battles waged between 1095 and 1291. The one-time journalist enjoys making academic writing accessible for popular audiences, and he said his book is merely synthesizing current research by others.
Stark balks at the theory, in vogue 30 years ago, that the Crusades were spurred on by the promise of wealth and land. The Crusades were bloody expensive, he argues, and far from being a profitable, colonial enterprise, they made paupers of princes.
Thomas Madden, professor of medieval history at Saint Louis University, agrees that recent analysis reveals the "crusades were a big money pit." He said it is important to understand the crusaders on their own terms, and, like Stark, he sees faith as their primary motivator.
"These were men who lived by the sword," Madden said. "They were keenly aware of their own sinfulness and their crusade was a way to get around damnation or at least a very long time in purgatory."
Despite noble intentions, the crusading onslaught recalls atrocities such as the Holocaust for Jews, said Talal Eid, founder of the Islamic Institute of Boston and commissioner on the U.S. Commission on International Religious Freedom.
"The term crusade," Eid said, "marks a painful time in the history of my kind, a painful era."
Despite that legacy, the word "crusade" resurfaced after both the Sept. 11 attacks and the intense European colonization of Muslim lands in previous centuries.
In 2001, former President George W. Bush called his nascent "war on terror" a crusade, alarming critics. Osama Bin Laden, too, has made use of the politically charged term.
"If you look at the fatwas of Osama Bin Laden or al-Qaida against the U.S. or the Western world, these fatwas are always called against crusaders and the Jews," Madden said. "They see the United States and Western Europe as crusaders always."
Stark knows his book will have its critics, including his own academic colleagues. He usually chooses the outsider role, preferring his home office to faculty meetings or campus politics.
In Christian circles, it's more of the same. Though he has defended the Lutheran faith of his North Dakota childhood, he is a reluctant Christian apologist.
"Answers of faith are always very complicated for me," Stark said. "I have always been culturally a Christian, committed to Western civilization, but I have to admit in parts of my life I was only culturally Christian. Slowly, I wrote my way to a more faithful position."
Stark does not worry about how his sympathetic portrayal of crusaders will be handled.
"If you sit there and worry about people misusing your stuff," he said, "you're never going to have anything to say."