The Association of Statisticians of American Religious Bodies (ASARB) has found that after Christianity, Islam is the largest religion in Illinois, with approximately 359,264 Muslim adherents in the state, or 2.8 percent of the population, compared with .8 percent of the U.S. population in total in a newly released study. (And some of them worship at the Orland Park Prayer Center mosque, pictured above.)
In an earlier study by the ASARB, there were found to be 51,442 Christian adherents per 100,000 persons in Illinois, the 18th highest in the country. (The state with the most Christians was Utah at 78 percent and the state with the least was Maine with just over 25 percent.) In Illinois, Catholocism in the largest Christian denomination with 3,648,907 followers, or 28.4 percent of the population (the fifth-highest of any state).
Though most Americans identify as Christian (more than three quarters, according to the survey), there are at least 236 discernable faith groups in the U.S., according to an earlier study by the ASARB. In Illinois, 7,094,832 people, or 55.8 percent of the population identifies with some religion.
In 20 states, mostly in the Midwest and the South, Islam was the second-largest religion, Judaism was the second-largest in 15 states, mostly in the Northeast, Buddism was the second-largest in 13 states, mostly in the Southeast and on the West Coast, Hinduism was the second-largest in two states, and the Baha'i faith was the second-largest in South Carolina.
This map from the study shows which states have which second-highest religion:
There are approximately 80,168 (.6 percent of the population) Conservative, Orthodox, Reform and Reconstructionist Jews in Illinois, who are .7 percent of the population in the U.S. There are 31,277 Buddhists (.24 percent) in Illinois, who are .32 percent of the U.S. population. There are 8,300 traditional Hindus (.06 percent) in Illinois, who are .08 percent of the U.S. population. There are 5,715 Baha'i in Illinois, or .04 percent of the population, and whose adherents make up .05 percent of the U.S. population.
Illinois has the number three-highest population of Muslims in the U.S. Compared with the other 50 states and the District of Columbia. Texas has the most and Hawaii has the least. Illinois has the number six-highest population of Reform Jewish people (the biggest individual Jewish population for which the study accounted) in the U.S. New York has the most and Wyoming has the least. Illinois has the seventh-highest population of Mahayana Buddhism adherents in the country, while California has the most and Wyoming has the least. Illinois the 11th-ranked state for traditional Hindus, with California having the most and New Hampshire having the least. Illinois has the ninth-highest number of Baha'i people out of every state, while California has the most and Rhode Island has the least.
While the second-largest religion statewide is Islam and in areas such as Chicago its suburbs and near East St. Louis and Springfield, there are areas in Illinois have other religions in the second spot. At least two counties in Illinois have Buddhism as their second-largest faith group and at least six counties have Judaism as the number two religion.
The ASARB has been helping to collect American religious data since 1952 and called the newly released study the most extensive.
This map from the ASARB study shows which counties in Illinois have which second-largest religion (Blue is Islam, pink is Judaism, yellow is Buddhism):
This ASARB map shows which religions, including Christian denominations, are popular in which areas of the U.S.: