[5][2][4] He made several trips playing the piano with the Young Collegians musical ensemble from Broadway Presbyterian Church and felt "strangely fulfilled" when asked to give his testimony one night, he later recounted in an interview, and also served as a leader at the Bowery Mission.

[5] While at Bob Jones University, where he gained a thorough knowledge of the Bible, Campbell preached as a ministerial student at Central Presbyterian Church in Anniston, Alabama, in 1944 and 1945.

[14] After playing college and NFL football, he attended Campbell's alma mater, Princeton Theological Seminary, and became an ordained Presbyterian minister himself.

Campbell's collected sermons preached at the Ann Arbor church are now archived at the University of Michigan's Bentley Historical Library.

[15] Campbell was called to be the first Presbyterian preaching minister at the interdenominational Riverside Church of 3,500 members in New York City in 1968.

Consequently, Campbell surprised the church board by announcing his resignation in June 1976, saying the administrative demands of his position had deprived him of "sufficient joy and satisfaction".

In 2005, he created the Ernest Campbell Endowed Fund in Homiletics to reward a graduating senior at Garrett–Evangelical Theological Seminary for outstanding preaching.

[18] Campbell authored three books: The Christian Manifesto, Where Cross the Crowded Ways, and Locked in a Room with Open Doors.

[10] Set to the tune "All Saints New" by Henry Cutler (1824–1902), it was added as an endpaper pastedown to the inside back cover of the Pilgrim Hymnal (1958) for congregational use at Riverside Church in the 1970s.

[9] A memorial service was held in September at Riverside Church, where he was extolled as "active on behalf of civil rights, migrant workers, a more humane national budget and fairer treatment for the LGBT community".