Among a dreary Republican field, Herman Cain stands out for using religious bigotry to gain political traction for his presidential ambitions.

Mr. Cain, a former pizza executive, started a few months ago by telling a reporter that he would not be comfortable with a Muslim in his cabinet. During a televised debate last month, he said his discomfort was due to the intention of some Muslims “to kill us.”

He quickly moved from that offensive and absurd generalization to advocating an overt violation of the Constitution. He traveled to Murfreesboro, Tenn., this month to make common cause with residents who are protesting the construction of an Islamic center there. The center, he said, is not “an innocent mosque,” because, he claimed, its supporters are trying to sneak Shariah law into American law.

He told Fox News that any community has the right to ban a mosque, because “Islam is both a religion and a set of laws, Shariah law,” he said. “That’s the difference between any one of our other traditional religions where it’s just about religious purposes.”