Contrary to what is alleged by bigots like Bill Maher, Muslims are 
not more violent than people of other religions. Murder rates in most of
 the Muslim world are very low compared to the United States.
As for political violence, people of Christian heritage in the 
twentieth century polished off tens of millions of people in the two 
world wars and colonial repression.  This massive carnage did not occur 
because European Christians are worse than or different from other human
 beings, but because they were the first to industrialize war and pursue
 a national model.  Sometimes it is argued that they did not act in the 
name of religion but of nationalism.  But, really, how naive.  Religion 
and nationalism are closely intertwined.  The British monarch is the 
head of the Church of England, and that still meant something in the 
first half of the twentieth century, at least.  The Swedish church is a 
national church.  Spain?  Was it really unconnected to Catholicism?  Did
 the Church and Francisco Franco’s feelings toward it play no role in 
the Civil War?  And what’s sauce for the goose: much Muslim violence is 
driven by forms of modern nationalism, too.
I don’t figure that Muslims killed more than a 2 million people or so
 in political violence in the entire twentieth century, and that mainly 
in the Iran-Iraq War 1980-1988 and the Soviet and post-Soviet wars in 
Afghanistan, for which Europeans bear some blame. 
Compare that to the Christian European tally of, oh, lets say 100 
million (16 million in WW I, 60 million in WW II–  though some of those 
were attributable to Buddhists in Asia– and millions more in colonial 
wars.)   
Or, between 1916-1917 Tsarist Russian forces — facing the Basmachi 
revolt of Central Asians trying to throw off Christian, European rule — 
 Russian forces  killed an estimated 1.5 million people.
  Two boys brought up in or born in one of those territories 
(Kyrgyzstan) just killed 4 people and wounded others critically.  That 
is horrible, but no one, whether in Russia or in Europe or in North 
America has the slightest idea that Central Asians were mass-murdered 
during WW I and looted of much of their wealth.  Russia at the time was 
an Eastern Orthodox, Christian empire (and seems to be reemerging as 
one!).
Then, between half a million and a million Algerians died in that 
country’s war of independence from France, 1954-1962, at a time when the
 population was only 11 million!
I could go on and on.  Everywhere you dig in European colonialism in Afro-Asia, there are bodies. Lots of bodies.
Now that I think of it, maybe 100 million people killed by people of 
European Christian heritage in the twentieth century is an 
underestimate.
As for religious terrorism, that too is universal.  Admittedly, some 
groups deploy terrorism as a tactic more at some times than others.  
Zionists in British Mandate Palestine were active terrorists in the 
1940s, from a British point of view, and in the period 1965-1980, the 
FBI considered the Jewish Defense League among the most active US 
terrorist groups. (Members at one point plotted to assassinate Rep. 
Dareell Issa (R-CA) because of his Lebanese heritage.)  Now that Jewish 
nationalsts are largely getting their way, terrorism has declined among 
them. But it would likely reemerge if they stopped getting their way.  
In fact, one of the arguments Israeli politicians give for allowing 
Israeli squatters to keep the Palestinian land in the West Bank that 
they have usurped is that attempting to move them back out would produce
 violence.  I.e., the settlers not only actually terrorize the 
Palestinians, but they form a terrorism threat for Israel proper (as the
 late prime minister Yitzhak Rabin discovered). 
Even more recently, it is difficult for me to see much of a difference between Tamerlan Tsarnaev and 
 Baruch Goldstein, perpetrator of the Hebron massacre.
Or there was the 
 cold-blooded bombing of the Ajmer shrine in India by Bhavesh Patel
 and a gang of Hindu nationalists. Chillingly, they were disturbed when a
 second bomb they had set did not go off, so that they did not wreak as 
much havoc as they would have liked.  Ajmer is an ecumenical Sufi shrine
 also visited by Hindus, and these bigots wanted to stop such 
open-minded sharing of spiritual spaces because they hate Muslims.
Buddhists have committed a lot of terrorism and other violence as 
well.  Many in the Zen orders in Japan supported militarism in the first
 half of the twentieth century, for which their leaders later 
apologized.  And, you had Inoue Shiro’s assassination campaign in 1930s 
Japan.  Nowadays militant Buddhist monks in Burma/ Myanmar are urging on
 an 
 ethnic cleansing campaign against the Rohingya.
 As for Christianity, the 
 Lord’s Resistance Army in Uganda initiated hostilities
 that displaced two million people.  Although it is an African cult, it 
is Christian in origin and the result of Western Christian missionaries 
preaching in Africa.  If Saudi Wahhabi preachers can be in part blamed 
for the Taliban, why do Christian missionaries skate when we consider 
the blowback from their pupils?
Terrorism is a tactic of extremists within each religion, and within 
secular religions of Marxism or nationalism.  No religion, including 
Islam, preaches indiscriminate violence against innocents.
It takes a peculiar sort of blindness to see Christians of European 
heritage as “nice” and Muslims and inherently violent, given the 
twentieth century death toll I mentioned above.  Human beings are human 
beings and the species is too young and too interconnected to have 
differentiated much from group to group.  People resort to violence out 
of ambition or grievance, and the more powerful they are, the more 
violence they seem to commit.  The good news is that the number of wars 
is declining over time, and World War II, the biggest charnel house in 
history, hasn’t been repeated.