At the top of the class were President Barack Obama with three A's, three B's and a C a modest mixed bag and former Utah Gov. Jon Huntsman with four B's and an A.
Former Massachusetts Gov. Mitt Romney racked up five C's, two A's and two A's.
The report card is the first ever issued for presidential candidates by the coalition, said SCA President Herb Silverman and is intended to help "secular-minded Americans" in the voting booth.
Most secularists, however, won't be voting in a GOP primary: data from the Pew Forum on Religion & Public Life show that religiously "unaffiliated" Americans tend to favor Democrats over Republicans, 55 percent to 23 percent.
"A lot of people in both parties have mentioned we have freedom of religion, but not freedom from religion," Silverman said. "We want to show that nontheists are an integral part of our culture and should be respected as much as people with other worldviews."
The Secular Coalition for America has 10 member organizations, including American Atheists, the Council for Secular Humanism and the American Humanist Association. Another 33 groups are "endorsing" organizations.
The coalition isn't alone in rating candidates against a specific agenda. John Green, an expert on religion and politics at the University of Akron, said political score cards have been used by everyone from organized labor to the Christian Coalition, and can be effective tools.
"First, they publicize candidates' and officeholders' positions and records from the group's point of view to the wider public," Green said. "Second, these report cards can be used to mobilize the group's members and supporters to vote for or against a candidate."
But how effective they are is debatable. Last year, a study by Georgetown University found that only 16 percent of U.S. Catholics were aware of a voting guide issued every four years by the U.S. Conference of Catholic Bishops, and only a quarter of those said it influenced their votes.
The coalition will issue an updated report card before the November elections, based on candidates' responses to a questionnaire. Silverman, whose group sent the guide to more than 35,000 supporters, said he was more disappointed than surprised by the grades.
"Some of the candidates continue to use their faith as a reason for promoting certain programs," he said. "I would rather they indicate why their positions are good based on secular reasons because they are supposed to be following our secular Constitution."