The first documented use of this term is found in notes from March 5, 1889, taken by Joshua Bailey during one of Mary Baker Eddy’s classes in Christian Science healing. Typically Eddy did not permit note-taking in her classes, but in this instance she invited Bailey (a former student and then the new editor of The Christian Science Journal) to take notes during her Primary class of February 25 – March 5, 1889. Eddy told the class that Christian Scientists could become members of the “mother church” in Boston, even “without their personal presence.” The term “mother church” was published for the first time in the April 1889 issue of The Christian Science Journal in an account of this March 5 class session.1 It appears the term caught on pretty quickly after that. It’s possible that the term may have been in use before 1889, but we don’t have any record of this. We also don’t have any information in our records as to why Eddy chose to use this term to describe the Church in Boston.
- Mary Baker Eddy, “The March Primary Class,” The Christian Science Journal, April 1889, http://journal.christianscience.com/shared/view/kxlrejhiyw?s=t.