Gallup recaps their findings:
Overall, 40% of Americans nationwide were classified as very religious in 2012 -- based on saying religion is an important part of their daily life and that they attend religious services every week or almost every week. Thirty-one percent of Americans were nonreligious, saying religion is not an important part of their daily life and that they seldom or never attend religious services. The remaining 29% of Americans were moderately religious, saying 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.The Friendly Atheist observes: "Incidentally (and also according to Gallup), Mississippi ranked at the top or near the top of the list of states when it came to obesity, inability to afford food, and least livable place. When people don’t have a lot going for them, it’s understandable they would turn to religion. If only they would realize God isn’t helping their situation."