I don't know of any other church or religion that refers to itself as "mother." Here, I believe, is the "smoking gun."
And upon her forehead was a name written, MYSTERY, BABYLON THE GREAT, THE MOTHER OF HARLOTS AND ABOMINATIONS OF THE EARTH. - Rev. 17:5
The Papal Archbasilica of St. John in the Lateran (Italian: Arcibasilica Papale di San Giovanni in Laterano), commonly known as St. John Lateran Archbasilica, St. John Lateran Basilica, St. John Lateran, or just The Lateran Basilica, is the cathedral church of Rome and the official ecclesiastical seat of the Roman Pontiff.
Here's the plaque that's outside the church:
"Sacrosancta Lateranensis ecclesia omnium urbis et orbis ecclesiarum mater et caput" ("Most Holy Lateran Church, of all the churches in the city and the world, the mother and head.") Inscription on the façade of the Basilica of St. John Lateran (Rome).