The Republican presidential primaries have followed patterns of a religious census. Mitt Romney has won wherever white evangelicals have cast a minority of the votes. Rick Santorum has won in most cases where white evangelicals cast the majority of votes. Mormon voters helped Romney win Nevada, Arizona and Idaho. But ironically, Santorum, a devout Catholic, has consistently lost the Catholic vote to Romney. Columnist E. J. Dionne Jr. thinks this is because Catholic voters tend to be a moderating voice in both parties and Santorum stands to the right of most Catholics who vote Republican. Except among Mormons, Romney doesn't do well with Republican voters who say a candidate's religion matters to them (Washington Post, March 21).