On November 4, the Dicastery for the Doctrine of the Faith published Mater populi fidelis (“The Mother of the Faithful People”), a Doctrinal Note “On Some Marian Titles Regarding Mary’s Cooperation in the Work of Salvation.” Signed by the Prefect, Cardinal Víctor Manuel Fernández, and the Secretary for the Dicastery’s Doctrinal Section, Monsignor Armando Matteo, the Note was approved by the Pope on October 7.
The Note provides a significant biblical foundation for devotion to Mary, as well as marshalling various contributions from the Fathers, the Doctors of the Church, elements of Eastern tradition, and the thought of recent Popes. Titles such as “Mother of Believers,” “Spiritual Mother,” “Mother of the Faithful” are approved in the Note. Conversely, the title of “Co-redemptrix” is deemed inappropriate and problematic.
In February 1996, the then-Congregation for the Doctrine of the Faith had discussed the request to proclaim a new dogma on Mary as “Co-redemptrix or Mediatrix of all graces.” Then-Cardinal Joseph Ratzinger was opposed to such a definition, arguing, “the precise meaning of these titles is not clear, and the doctrine contained in them is not mature. […] It is not clear how the doctrine expressed in these titles is present in Scripture and the apostolic tradition.”
A more in-depth explanation of Mater populi fidelis can be found here.