Is Islamic Law a Threat?

In the article of New York Times, Islamic law in America is being discussed in terms of its possibility in a Judeo-Christian society. This article is written by Eliyahu Stern, and is around of mostly a fear about Islam. He says according to the Tennessee General Assembly, Shariah (Islamic Law) promotes "the destruction of the national existence of the United States." In addition, in the article Stern quotes words of Newt Gingrich, the Republican presidential candidate, that "Shariah is a mortal threat to the survival of freedom in the United States and in the world as we know it."

Eliyahu Stern thinks of these ideas as "exactly wrong" because such notions are contrast with America's successful history of religious tolerance and American democracy. Also he compares such notions to a thought in 19^th century in Europe, Jewish law is seditious.  However, Gingrich said in a speech to the American Enterprise Institute in Washington in July 2010 that "Stealth jihadis use political, cultural, societal, religious, intellectual tools; violent jihadis use violence, but in fact they’re both engaged in jihad, and they’re both seeking to impose the same end state, which is to replace Western civilization with a radical imposition of Shariah.”

I think these explanations are very important to show American freedom of thinking and anti-Islam movements. But Muslims are a reality of modern time in the world. They have specific beliefs, life style, and inherently rules. American laws either are based on secularism or on Christianity. For both cases, Muslims become excluded from the constitution.

 

Frankly, "As a body of Islamic scholars, we the members of Fiqh Council of North America believe that it is false and misleading to suggest that there is a contradiction between being faithful Muslims committed to God (Allah) and being loyal American citizens," the fatwa declared." However, I am thinking that if there is not a conflict between Shariah and the Constitution, why do some people like Gingrich consider Shariah as "the destruction of the national existence of the United States", or "a mortal threat", etc?

Maybe the Constitution reflects a Christian identity, thus radical Christians do not want Islamic law or maybe being an American requires being a Christian. We can think about many things which can be the reason. But I have three questions that even if Gingrich is correct on his idea, while there is a religious freedom in the USA, and Islam is a religion, what is the obstacle to establish Islamic law? Second is that if there is not an essential conflict between being faithful Muslims and being loyal American as FCNA claimed, why cannot people choose a different rule for their own lives? Third, is if the establishment of Shariah is a threat for the existence of the American nation or Christian America?