A study measuring religious bodies in the United States called the, “2010 U.S. Religious Census: Religious Congregations & Membership Study (RCMS)” was recently released by the Association of Statisticians of American Religious Bodies (ASARB). The most comprehensive study of its kind, it provides detailed county-by-county information on congregations, members, adherents and attendance for 236 different faiths groups. (The survey differentiates between specific denominations within the same tradition.)
The researchers found Utah to be the most Christian* state with around 78 percent of population identifying as Christian adherents. The researchers found Maine to be the least Christian state with only about 27 percent identifying as Christian adherents.
The researchers define adherents to be those with an affiliation to a congregation including children, members and attendees who are not members, and believe that the adherent measure is the most complete and comparable across religious groups. Congregations are defined as groups of people who meet regularly at a pre-announced time and location.
More than 150.6 million Christian adherents and 344,894 congregations were reported across the country. It is noteworthy that less than 50 percent of of the nation's population identified as Christian adherents. With close to 15.8 million Christian adherents, California reported the highest number of Christian adherents, whereas Vermont reported the lowest -- only 200,000 identified as Christian adherents. Around 10 percent of the nation's Christians reside in California. With 27,248 congregations, Texas reported the highest number of congregations in a state, whereas District of Columbia reported the lowest with 566.
As illustrated in the map below, states where more than 55 percent identified as Christian adherents were in the South and Midwest. States where less than 36 percent identified as Christian adherents were in the West and Northeast. This pattern closely reflects where the most religious cities in the United States are located.