Answer:
I believe that the American citizens would be worried for one thing. The Bill of Rights contained the rights that people have as an American and if those rights were striped away from them like that, it would bring fear to Americans across the country. It's like taking away people's humanity.
The south states of the United States
In 610 CE, the prophet Muhammad has a vision that ultimately led to the creation of Islam. However, when Muhammad died in 632 CE, people disagreed over who should succeed him as caliph. The Sunnis believed that Abu Bakr (his successor) was the right choice, which the Shiites disagreed, believing that the next caliph should've been Ali, Muhammad's brother in law. Still to this day, there is a definite split, and while they both have the same fundamental beliefs, neither get along well. This issue is especially prevalent in the Middle East where the majority of people are Sunnis, however the Shiites do not want them to hold power, so rebellion occurs. Likewise, when the Shiites gain power, the Sunnis rebel. The terrorist group ISIS is technically fighting for the Sunnis, however it is important to note that they practice a very radical form and do not represent the beliefs of most Muslims.