It's been said here before but it bears repeating: Islam is not just a religious faith that includes some rules of conduct for followers. It contains a body of religious and civil law for governing the people in the lands under Islamic control. This would be referred to as Sharia law. Those who adhere to to the faith are expected to follow Islamic law even when it conflicts with the laws of any government that may already exist.
Much of Sharia law is incompatible with our Western legal traditions. Specifically, it cannot be reconciled with our Constitution. Many of the provision of Islamic law are anathema to our culture and its traditions. An example of this incompatibility is illustrated on page two.