Gallup classifies Americans as “very religious” if they say religion is an important part of their daily lives and that they attend religious services every week or almost every week. That group constituted 41% of all U.S. adults in the first half of 2014. “Nonreligious” Americans (30% of Americans in 2014) are those who say religion is not an important part of their daily lives and that they seldom or never attend religious services. The remaining group, 29%, are classified as “moderately religious.” These people say religion is important in their lives but that they do not attend services regularly, or that religion is not important but that they still attend services.

From 2008 to June 2014, nonreligious Americans have been the most Democratic of the three religious groups, with a net Democratic value ranging between +38 and +19 over that period. Those who are moderately religious have also tilted Democratic, with net values ranging from +23 to +1. Those who are very religious are least Democratic, with net values in the negative range, meaning that on average, this group identifies with or leans toward the Republican Party more than the Democratic Party.