So wtf was the point of saying it then? As I already said most Muslims don't live according to sharia law so his statement kinda contradicts his ideology of not playing "what ifs" cus that is a pretty damn bug what if imo.
As you stated the American public as a whole would never stand behind a president who practices sharia law or any religious extremist for that matter. As many already said the constitution keeps church and state separate so he is just trying to fear monger.
And yeah, even his explanation still pretty barbed towards Islam as a whole
"He said if someone could show him an Islamic text that opposes Sharia law, he would change his mind about a Muslim’s ability to be commander-in-chief of the United States.
“But right now, when you have something that is against the rights of women, against the rights of gays, subjugates other religions, and a host of things that are not compatible with our Constitution, why in fact would you take that chance?” he said."
http://m.washingtontimes.com/news/2015/sep/27/ben-carson-gop-presidential-candidate-show-me-an-i/