Mercer County, Illinois has 55 churches in the Churches List directory, 0 of them verified and 13 with a published website. The 2020 US Religion Census counted 33 congregations and 5,742 adherents across 13 religious bodies in the county. That is 366 adherents per 1,000 residents of its 15,698 people.
| Religious body | Congregations | Adherents | Per 1,000 pop. |
|---|---|---|---|
| Evangelical Lutheran Church in America | 5 | 1,570 | 100.0 |
| Catholic Church | 3 | 1,500 | 95.6 |
| United Methodist Church | 7 | 1,179 | 75.1 |
| Presbyterian Church (U.S.A.) | 7 | 570 | 36.3 |
| Non-denominational Christian Churches | 2 | 340 | 21.7 |
| Southern Baptist Convention | 2 | 206 | 13.1 |
| Presbyterian Church in America | 1 | 183 | 11.7 |
| Jehovah's Witnesses | 1 | 112 | 7.1 |
| Assemblies of God | 2 | 79 | 5.0 |
| Baha'i Faith USA | 0 | 3 | 0.2 |
| Christian Church (Disciples of Christ) | 1 | 0 | 0.0 |
Source: 2020 US Religion Census (Association of Statisticians of American Religious Bodies). Per-1,000 rates divide reported adherents by the county's 2020 Census population (15,698). Largest 12 bodies by adherents shown.
Directory traditions here: Presbyterian (9) · Methodist (8) · Evangelical (6) · Catholic (6) · United Methodist (5) · Lutheran (4) · Baptist Churches (4) · Non-Denominational (3) · Church of the Nazarene (2) · Missionary (1)
Directory listings are mapped to Mercer County through the US Census Bureau's 2020 ZCTA-to-county relationship file: each ZIP Code Tabulation Area is assigned to the county holding the largest share of its land area, so a small number of churches in ZIP codes that straddle county lines may be attributed to a neighboring county. Congregation and adherent counts come from the 2020 US Religion Census and are reported by the religious bodies themselves. Population is the county's April 2020 decennial-census base from the US Census Bureau's population-estimates program; per-1,000 adherence rates divide reported adherents by that figure. Corrections to any listing go through the corrections page.