Barack Obama is taking heat for drawing comparisons between religiously-motivated (primarily Islamist) violence today, and Christianity's role in violence related to the Crusades, Inquisition, slavery and the Jim Crow era. Political opponents are using the not-very-smart-statement to criticize Obama, worsening our political discourse.

For starters, here's what Obama said. I'm quoting at length for context -- the bolded sentences are the ones that have his critics in an uproar.

So how do we, as people of faith, reconcile these realities -- the profound good, the strength, the tenacity, the compassion and love that can flow from all of our faiths, operating alongside those who seek to hijack religious for their own murderous ends?
Humanity has been grappling with these questions throughout human history.  And lest we get on our high horse and think this is unique to some other place, remember that during the Crusades and the Inquisition, people committed terrible deeds in the name of Christ.  In our home country, slavery and Jim Crow all too often was justified in the name of Christ.  Michelle and I returned from India -- an incredible, beautiful country, full of magnificent diversity -- but a place where, in past years, religious faiths of all types have, on occasion, been targeted by other peoples of faith, simply due to their heritage and their beliefs -- acts of intolerance that would have shocked Gandhiji, the person who helped to liberate that nation.
So this is not unique to one group or one religion.  There is a tendency in us, a sinful tendency that can pervert and distort our faith.

Obama essentially seems to be simply saying that "we're all sinners; and let he who is without sin cast the first stone." But by fleshing that out with specific historic examples -- the Crusades, the Inquisition, slavery -- he's inviting us to weigh very different forms of violence and suffering against each other, which is not typically a smart idea.

On the one hand, by any objective measure the Crusades and slavery were far more barbaric enterprises than contemporary global Jihadism. Historian Matthew White, who literally wrote the book on human atrocities, puts the death toll from the Crusades at around 3 million, and the Atlantic slave trade around 16 million. By contrast, only ("only") 107,000 people have been killed in global terrorist incidents since 2000, according to the Institute for Economics and Peace.

Of course, if you think about this for a bit you start to see the problems with the comparison. Some slave traders may indeed have sought justification for their actions in the Christian faith, but much of the trade was driven by economic reasons (a demand for cheap labor) and racism. The Crusades were just as much about political power as they were about religion.

And so, Obama's drawing parallels between today's acts of violence in the name of Islam and acts of violence through history in the name of Christ omits a key nuance. Violence, some of it religiously-motivated, is a common denominator across time and place. But the reasons of individual acts of barbarism are each unique and different in their own awful ways.

But the evidence also shows that religion has become a much more powerful motivator of terrorism in the past 15 years or so. The chart below, from the Institute on Economics and Peace, shows that the number of terrorist incidents driven by religion has increased dramatically since the year 2000.

And most religiously-motivated terrorism today is perpetrated by Islamist terrorists in the name of their misreading of Islam. Fully two-thirds of terror-related deaths in 2013 were caused by just four Islamist groups -- Al Qaeda and its affiliates, Boko Haram in Nigeria, the  Islamic State, and the Taliban.

There is one useful comparison between slavery and contemporary Islamist terrorism that Obama left unmade. If Christianity was indeed one of the drivers of the slave trade, it was also instrumental in the dismantling of the practice. Similarly, it may be that the best way to defeat Jihadist extremism is through reform from within -- rather than via military might from without.