Illinois - State Membership Report (2020)
Exact definitions of "congregations" and "adherents" vary by religious body. Congregations may be parishes, churches, synagogues, mosques, temples, or another site where a religious body has regularly scheduled worship services. Adherents generally are members, children who are not members, and others who are not members but are considered participants in the congregation.
Religious Traditions (1980 - 2020), Percent of Population
The population of this state was 12,812,508 in 2020. The adherent totals of the religious groups listed above (6,510,363) included 50.8% of the total population in 2020. The adherence rate is the number of adherents of a given group per 1,000 people in the general population.
Note that data collection methods for religious bodies change over time, affecting the comparability of statistics. For further information, see the U.S. Religion Census website at https://www.usreligioncensus.org/.
The 2020 data were collected by the Association of Statisticians of American Religious Bodies (ASARB) and include data for 372 religious bodies or groups. Of these, the ASARB was able to gather data on congregations and adherents for 217 and on congregations only for 155.[More information on the data sources]