There are regions in the world where the prominence of Islam as the dominant power controlling peoples' lives is being challenged. This is a good thing, it is far better to be governed by a system that is modern, and designed is to operate in the modern world. Democracy has its problems, but give me democracy over religion any day.
The problem with creating a working, fair, democracy is the fine-tuning on the 'checks and balances', ensuring that no one individual or interest group has disproportionate control over any other. The US system is, in theory at least, a fine balance between the executive, legislative and judicial branches. In the Westminster system the executive is dependent on the support of the legislative branch, so the balance is effectively between the legislative and judicial branches, with the legislative process being steered by the executive.
Why all this discussion on legislative branches and whatever else? The answer is that it shows the flexibility of the systems to govern the people. To create a new law requires the approval of the legislature, it's enforcement depends on the judiciary. Without checks and balances the executive could take control of both the law making and the law enforcement.
Now if the executive also has a firm belief in a certain well known Bronze Age text the results can be one hand comical, but in the bright light of day 'ludicrously tragic'.
Hence we have Al Qa'eda in Iraq banning women from buying cucumbers. Perhaps the most ridiculous of religious laws I've heard in a long time.