I'm a little short on time so I will have to revisit this topic later but I wanted to write it down before I headed out.
I have occasionally contended that Islam is an ideology that is also a religion. The religion part I have no problem with. But the ideology I do. I believe there is something inherent in the Islamic ideology that promote violence and intolerance.
But let's put that aside for a moment and look at Communism.
Communism, as an ideology IS peaceful. The theory behind communism is that we all work together to contribute to the whole of society equally. We do what we're best at to help society as a whole. It is a Utopian philosophy.
Yet, Communism resulted in the deaths of more human beings in history than any other ideology (Fascism is a distant second).
Why is this? Because for whatever reason, Communism seems to lead its most vigilant believers into enacting policies to enforce the ideology which results in deaths. Because most people aren't natural communists (not all people contribute equally) the "true believers" realize they have to force them to adhere to communism. When this is done, the results are catastrophic (famine being the biggest problem but elimination of non-believers as well).
Christianity had its issues as well. In Christianity, only those who accept Jesus Christ as their lord and savior have the ability to go to heaven. Therefore, the true believers went to great lengths to convert as many people over in order to "save them". Zealots ultimately killed thousands of people in the process of doing this. But the "save them" part of Christianity is, in my view, not potent enough to be really considered an ideology.
The point is, ideologies have different effects on the truly hard core. To know whether an ideology is a problem or not we have to look at it over a long period of time and on a global scale. We need to make sure that it isn't local culture, or race, or local politics getting intermixed in with the actions of people who adhere to a particular religion or ideology.
That is why I see Islam as a dangerous ideology. That no matter where you go, no matter how materially content they are, they are much more prone (as a percent) than believers in other religions to violence and intolerance.
And just as with Communism, which in itself is a Utopian philosophy that contains no violence at its core, Islam seems to cause its true believers to be much more likely to do things that are very very bad.