I think that civilizations don't clash, and am amenable to the idea that democracies are less likely to clash.
What causes confusion, I think, is, as Gandhi is reported to have said when asked what he thought about Western Civilization, "Great Idea! They should try it!": we haven't really tried it, and the clashes we are having are the result of it.
Consider the possibility that the concept of the Ummah is more well-formed sociologically than the concept of Western Civilization, i.e. it is a worked out and planned result of a consistent and coherent world-view threshed out by centuries of commentary and discussion (ijtihad)
Consider also that it is much more likely that a civilization will clash with a mere collection of warring states, or with an Empire.
A historical look at the formation of nation-states (which, I understand, Islam does not formally contemplate, thinking more of an eventual worldwide theocracy with perhaps divisions corresponding to ethnicities, but not separate uses of power) does not give me the idea that there is anything to the idea of nation states except an agreement not to interfere in the maltreatment of a state's citizens. That's a step backwards from human morality. RealPolitik of the worse kind.
Western Civilization, as we like to call it, is currently stagnating in the philosophical backwater of what might be called opinionism, the idea that there is no way to finally settle questions of cultural correctness, which implies that cultural conflict is a given.
We give you toothless resolutions on Rwanda, Darfur, Palestine, Israel, and the USA. No real functionality.
Be that as it may, Islam seems to have no such qualms about prescribing morality by interpreting revealed wisdom. The problem seems to be now that the practice of interpretation has become as hidebound as the practices of the Catholic Church just before the Reformation. We await the Muslim Martin Luther.
However, can the ineffectuality of current social science, best characterized by the United Nations' weakness, stand against the social organization that is the current coalescing Muslim Empire, which is being whipped into shape by reaction against the crazed superpower, the United States?
Should it occur to fight the battles on the canvas, instead of standing, with rifles and IED's instead of nukes and cluster bombs, a billion or so socially coherent Muslims might be a match for the West.
This problem defines an important aspect of the drive to capture the government from the fundamentalists of the American Exceptionalist Institute, whatever its current misnomer may be.
It may be that democracy, however flawed in relation to its goal of happily governing humans may be, is better in the long run than Islam, even in its finest hours, but the conflict is not, I think, going to be lessened by our present greedy, brainless course of action.
This is why we fight for Democratic candidates. In many ways, our desire for diplomacy, health care, governmental handling of the tragedies of the commons, and a unified and peaceful society are exactly the goals of the social ideals of the successful Ummah.
The religious theory might be negotiable in some way, if we can get reasonable people to the table instead of the current fundamentalist Bin Ladens and Bushes.