I'm not sure the religion of the respective people committing acts of violence and oppression is really an important factor, or even the most important factor, even when these acts are committed in the name of that religion. Maybe demographic and social factors have much more impact, and the respective religion serves as catalyst only?
Now I may be wrong, and rely too much on the idea that reality shapes consciousness more than vice versa, in this case, but there are historical and sociological works that suggest such factors are usually related to trouble.
For example, after Spain's "Reconquista" (the fight to topple Muslim rule in the 15th century), the country started conquering America, violently christianizing and enslaving native American peoples. Both, Reconquista and Conquest, could only happen -- or more or less had to happen -- because at that time, demographics in Spain were of a kind that provided a large excess of young males ready to fight, which, otherwise, would have had a very hard time to find a basis for life if the monarchy had not sent them to pillage. The rulers had a large resource of motivated potential soldiers and colonizers as carrot, and the problems that would have arised had these many young males not be provided with a purpose, as a stick. It was a no-brainer they chose to expand. It was not Christianity that caused them to do it. The prevalence of Christianity just resulted in Spain chosing it as justification, motivator and means to foster identity.
Today, many Muslim countries face a critical demographic situation. Their economic development is poor, some are just beginning to emerge economically, improvements in medicine and sanitary measures have caused a huge spike in the birthrate in the last generation. Traditional family and social structures and attitudes are still dominant, but already very much challenged by new technology and globalization, and by a vast increase of general education in the last generation.
So we have many more young people in Muslim countries than old, many of them much better educated than their parents and grandparents, a transformation process that changes social structures that had been intact for hundreds of years and an according confusion, especially among older people who can't keep up to date, are scared, and resort to old traditions and religion even stronger. Also, there is a huge excess of young males with few economic prospects.
When Europe was in a similar situation of economic, technological and demographic transformation in the late 19th and early 20th century, we saw a rise of general militarism and an expansionist sense of superiority and mission, that first resulted in the colonization of Africa and much of Asia, then in the rise of totalitarian ideologies like communism and fascism, and two World Wars.
At the turning point from traditional social structure to modern way of life, many people, especially young males who had no prospects due to unfinished economic development, fled into the arms of ideologies that combined old tradition with expansionist and revolutionary violence, a reactionary result of confusion -- in case of Germans, it was Nazism (a perfect example for a new, reactionary ideology that combined "modern" revolutionary thought with tradition!), in case of many Muslims today, it's radical Islamism (which, as many experts claim, is distinctively different from orthodox and classic Islam, insofar it is more expansionist and violent, and combines modern ideas with tradition -- and thus is just as reactionary as Nazi ideology was).
Only when the economic and technological transformation had reached a certain point, so that general wealth had reached even the lower classes, reformed social structures caused the birthrate to go down again, and many "excess" young males had been killed as cannon fodder, Europe found peace and rolled back its expansionism and sense of mission.
So does it really matter that much which religion someone believes in, to determine his people's violence or thirst for expansionism? I'd guess that when you have a good job, a nice house and you are generally satisfied, you won't be going to commit suicide bombings, no matter how much your belief glorifies that. And when you're poor, young, confused because new ideas and technologies transform the world so much you don't understand it anymore, and because your struggling economy can offer you no prospects, it's very likely you'll look for scapegoats, trust hate preachers who promise a shining future or resort to violence -- even if you have no religion, or if your religion does not really condone that.
That's just the general idea. It doesn't mean there are no exceptions.
