According to a CNN exit poll of South Carolina Republican primary voters, Newt Gingrich, a thrice-married Catholic, won twice as much support from evangelical Protestants as Mitt Romney, a Protestant. And among voters for whom religion meant “a great deal,” 46 percent voted for Mr. Gingrich and only 10 percent for Mr. Romney.

This is the second evangelical-heavy state Mr. Romney has lost. With a third, Florida, next on the list, it’s important to consider the often antagonistic skepticism that many evangelicals have of Mr. Romney’s brand of Protestantism: Mormonism.