It is reasonable to assume that a historical episode which took place almost 1,000 years ago would no longer be politically controversial today.
But, as United States President Barack Obama recently discovered, even that cannot be taken for granted.
Christian organisations throughout America erupted in anger when Mr Obama made a passing reference earlier this month to the Crusades as a period of "terrible deeds" and a reminder that, just as "twisted and distorted" people commit crimes in the name of Islam today, so did previous generations of Europeans in the name of Christ.
Some argued that it's offensive to make any "moral equivalence" between the Crusades a millennium ago and Islamic extremists today. Ms Star Parker, a noted conservative columnist, went as far as to claim that she was subjected to "verbal rape" by the President.
Strong stuff indeed. But most of the arguments on both sides of this Crusades debate are either factually incorrect, or dangerous political nonsense. Such historical references don't illuminate or inform the current de bate about the connection between faith and bloodshed. Nor can they justify or even explain the current phenomenon of terrorism.
Different religions, similar zealotry
LIKE all historical comparisons of this kind, the similarities between the religious zealots who initiated the Crusades and those who today espouse jihad appear to be very strong on the surface.
The Crusades were a series of military campaigns organised by the Roman Catholic Church to "liberate" Christianity's holy places in Palestine from Muslim rule - particularly the Holy Sepulchre, the place where Jesus was crucified and buried.
Like jihad, the Crusades amounted to a "holy war" in the name of Christianity.
And, like the proponents of jihad, the Crusades attracted volunteers from everywhere.
Countries and languages did not matter, as people from as far as Spain or Scandinavia left their families and all their belongings and literally marched to Palestine, a land of which they knew nothing about, and which many of them never lived to see - just as the misguided Europeans who currently volunteer to fight in Syria and Iraq may end up being cannon fodder, killed within days after their arrival.
The propaganda which justified the Crusades was as shocking and as false as that used by recruiters to terrorism today.
Christians were asked to fight to save their brethren in the Holy Land, who supposedly had their innards yanked out through their belly buttons by Muslims.
Much of the killing which the Crusaders perpetrated had nothing to do with fighting Muslims for possession of the holy places; a great deal of it took place in Europe, as columns of men made their way to the Middle East, killing, raping and stealing their way through the continent.
This, too, is similar to the terrorists today who, in their fight against the "infidel", end up killing mostly fellow Muslims.
And even by the miserable humanitarian standards of warfare at that time, the Crusaders were astonishingly cruel towards the people they defeated.
When they marched into Jerusalem on the morning of July 15, 1099, the Crusaders butchered the entire Muslim population - an estimated 70,000 people.
There were no videos of these murders but, according to contemporary accounts, the Crusaders who first entered Jerusalem barefoot quickly acquired "shoes", formed from the coagulated blood of the murdered people which stuck to their feet.
Overall, it is estimated that one million people perished in the Crusades - one in 10 of the population of Europe at that time, and about the total population of Britain in the 11th century.
And in an eerie reminder of terrorists today, Crusaders also believed that, if they died in battle, all their sins would be forgiven and they would go straight to heaven.
Their actions were justified in religious terms.
The blood-curdling exhortations of Crusader leaders read rather like the meanderings of Osama bin Laden or Abu Bakr al-Baghdadi, the current leader of the Islamic State in Iraq and Syria, full of grotesque misrepresentations of their respective faiths, peppered with quotes from holy books, usually lifted out of context.
So, if the similarities between Christian violence a millennium ago and those of Muslims who espouse violence today are so striking, why the outcry over Mr Obama's comparisons?
Different historical context
THAT is largely because the differences between these two historical episodes are far too great to draw any meaningful conclusions.
The Crusades took place over 200 years, spanning 12 European generations. None of the people who fought at that time knew of the word "Crusade" or called themselves Crusaders as such; the term entered European languages only in the 17th century.
To suggest that all Crusaders were inspired by religious fanaticism is wrong.
People fought for many reasons, including honour, chivalry - most chivalric orders, including the St John's Order which operates ambulances today, hail back to those times - loyalty to their prince or king, or the simple camaraderie of young men who went to fight from the same village.
Crusaders felt themselves under attack from Muslims, an undeniable reality since Muslim armies already ruled Palestine and were closing in on Europe in a pincer movement from the Balkans on one side and Spain on the other.
So, what to us looks like a dark episode of Muslim-bashing was perceived at the time as legitimate self-defence.
Some Crusades never aimed to reach the Holy Land, and were used instead to settle scores between European princes.
Some were just pathetic, like the so-called Children's Crusade of 1212 when, responding to a call of one boy who claimed to have been told by Jesus to work for the peaceful conversion of Muslims to Christianity, thousands of teenagers from France and Germany went on the march to the holy places.
Most either drowned in the Mediterranean Sea or were sold into slavery in North Africa.
Alongside the undeniable cruelty, there was also much progress.
Europe's road network and shipping lines owe their origins to the Crusades.
Ironically, much of the law of warfare which operates today also originated at that time. And, just as ironically, many of the warfare techniques which subsequently made the Turks such fearsome fighters were also perfected as a result of fighting Crusaders.
That is why in many Christian countries, the concept of a "crusade" retains positive connotations. Politicians sometimes refer to crusades against crime or poverty as expressions of determined action. Reducing all of this past to just a bunch of religious nutters who strutted across Europe to kill Muslims is to render history as a parody.
One can understand why Muslims dislike the idea that the Crusades can ever have a positive meaning.
Former US president George W. Bush's use of the term in the context of the fight against terrorism was certainly misguided.
But it's also worth noting that some Muslim leaders have used the Crusades to justify their own call for violence.
It is noticeable, for instance, that those who are most fond of reminding the faithful of the horrors of the Crusades are largely the terrorist leaders of today.
For most of the moderate Arab leaders, the Crusades are history, as they should be.
Perhaps Muslims everywhere should be reminded of an often-neglected aspect of the Crusades: that, ultimately, the Crusades failed and the Muslims won.
By the end of the 13th century, Muslims were back in control of the Middle East and, two centuries later, they were in central Europe.
The Crusades can, just as plausibly, be portrayed as a tale of endurance and triumph by the Muslims, the way Muslim history presents the Ottoman conquests of the Balkans or of Spain, neither of which were exactly bloodless.
Either way, the safest bet for someone like Mr Obama is to avoid repeating simplistic historical analogies which offend some Christians without reassuring most Muslims.
Nobody denies that all religions are capable of generating violence, and nobody is suggesting that any of the world's great religions advocates violence as its main objective.
That is enough for an American president to say; the rest should be left to trained historians, which neither he nor his speech-writers evidently are.
Perhaps the truly enduring moral to this episode is that all politicians should go easy on historical analogies; not only are they liable to be misunderstood, but invariably they also confuse rather than clarify matters.