If Newton Leroy Gingrich becomes the Republican candidate for president of the United States, then the 2012 election will be a contest between two men who found new religions fairly late in life. Gingrich is on his third religion: He was raised a Lutheran, later became a Southern Baptist, and in 2009 was received into the Roman Catholic church. President Obama, having been raised in an irreligious home, famously found faith as an adult in Chicago, where he was baptized in 1988 by Rev. Jeremiah Wright Jr. (of great controversy).

Gingrich and Obama are hardly unique in the annals of contemporary politics. Major American politicians seem unusually promiscuous in their religious affinities, not just switching houses of worship but totally altering the substance of their...