Ben Carson's Business Manager on a Muslim in the White House: "Not an issue of religion, it is an issue of one's belief system."

According to Politico, Ben Carson’s business manager Armstrong Williams told CNN’s Alisyn Camerota this morning that Carson’s rejection of the possibility of a Muslim president was “not an issue of religion, it is an issue of one’s belief system, of how they will govern.”聽
Someone needs to tell Carson that religions and beliefs systems have a lot in common. Whatever one calls one’s belief system, the Constitution forbids a religious test. Carson is making this unnecessarily difficult.
Carson said there are tenets of Islam which sanction the killing of gays and Jews. Does he not realize what Leviticus says? Is he unaware that some Christian movements have advocated hatred toward Jews?
Carson and his handlers are stereotyping Muslims and displaying group-serving bias regarding Christianity. 聽One knows the diversity of a social group to which one belongs much better than to an out group. Carson has lumped all Muslims into his stereotyped view of Islam while ignoring similar elements within his own religion.