From its inception, the Free Church was associated with prominent figures, both local and national. One of the church's founders was a personal acquaintance of Abraham Lincoln. The church's first pastor, Rev. Leonard Collins, publicly debated famed abolitionist Frederick Douglass on the issue of whether African Americans should establish their own independent churches.
Perhaps the most famous member of the Free Church was John Brown, who lived in Springfield from 1846 to 1849. Brown was already a committed abolitionist before moving to the city, which had a well-established reputation as a hotbed of anti-slavery activity. During his time in Springfield, Brown not only attended the Free Church, he was also closely associated with the African American community, becoming friends with Thomas Thomas and his family, and meeting Frederick Douglass when he visited Springfield. A rocking chair that Brown gave Thomas's mother is on display at the Wood Museum of Springfield History. The church proudly displays a Bible once owned by Brown.
In 1892, the Sanford Street Church merged with the Quincy Street Mission to form St. John's Congregational Church, which was named in honor of John Brown. By the late 1890s, the church was nationally known for its neighborhood outreach programs. Among the programs run by St. John's were night classes for women who worked as domestics and Camp Atwater, the longest continually-run camp for African Americans in the United States.
In the twentieth century, the church continued its long tradition of involvement in social justice causes by becoming involved in the civil rights movement in New England under the leadership of Rev. Charles E. Cobb. A well-educated man, Cobb led a campaign to force the Springfield School Board to end its discriminatory practice of not hiring qualified African American teachers. Cobb was also one of the first religious leaders to address environmental racism, such as dumping toxic waste in communities where most residents were poor people of color.
St. John's Congregational Church was added to the National Register of Historic Places in 2016.