Church as an organization
Primatial local Churches
The "first see", or primatial see, of a regional or national church is sometimes referred to as the Mother Church of that nation. For example, the local Church of Armagh is the primatial see of Ireland, because it was the first established local Church in that country. Similarly, Rome is the primatial see of Italy, and Baltimore of the United States, and so on.
The first local church in all of Christianity is that of Jerusalem, the site of the Passion of the Christ and of Pentecost, making it the Mother Church of all Christianity.
This term is most often used among Roman Catholics as Holy Mother Church. The Church is considered to be a mother to her members because she is the Bride of Christ, and all other churches have had their origin or derived from her. Another term used in the Catechism is the title "Mater et Magistra" (Mother and Teacher). Pope John XXIII made this the title of his encyclical celebrating the seventieth year after Leo XIII's groundbreaking social encyclical, explaining that in this Mother and Teacher all nations "should find ... their own completeness in a higher order of living." Pope Francis said:
The Church is our mother. She is our "Holy Mother Church" that is generated through our baptism, makes us grow up in her community and has that motherly attitude, of meekness and goodness: Our Mother Mary and our Mother Church know how to caress their children and show tenderness. To think of the Church without that motherly feeling is to think of a rigid association, an association without human warmth, an orphan.
In Anglicanism, the Church of England gave rise to all the other Churches in the Anglican Communion, and as such she is considered the Mother Church. The Archbishop of Canterbury thus serves as the focus of the Anglican Communion.
In Methodism, the Methodist Church of Great Britain is considered the Mother Church by all the other Methodist Churches in the World Methodist Council, with Methodist Central Hall often being a symbol of this tradition. This is because the Methodist Church of Great Britain "gave birth to the whole Methodist enterprise and then of a nineteenth-century church whose influence reached out across the world through the missionary endeavors of the various British Connexions within and beyond the British Empire."
National Baptist Convention
The National Baptist Convention, USA, Inc., is often referred to as the "mother church" among African-American Baptists. This Convention is the oldest and largest of the Conventions and all other National Baptists trace their origin to her. Also, several large Pentecostal Organizations regard this convention as their mother church.
"Most Holy Lateran Church, of all the churches in the city and the world, the mother and head" ("Sacros[ancta] Lateran[ensis] eccles[ia] omnium urbis et orbis ecclesiarum mater et caput") Inscription on the façade of the Archbasilica of St. John Lateran
Apostolic Sees or Ecclesia matrix
Apostolic sees are those local churches founded by one of the Twelve Apostles or Paul the Apostle. In 1855 Bingham wrote: "Ecclesia matrix, a mother-church, is sometimes taken for an original church planted immediately by the Apostles, whence others were derived and propagated afterward. ...And in this sense the Church of Jerusalem is called 'the mother-church of all churches in the world.'"
He also refers to "Arles the mother church of France, supposedly planted by the Apostle's missionary Trophimus, first bishop of the place."