"Following Paul in Ephesians 5, the patristic tradition has understood what is said of [Mary] to be said of the Church. The degree of this identification is disputed, particularly in the context of the 'co-redemptrix' title, whose legitimacy was debated in the 1940s and 1950s, and resisted as if implying a species of synergism.... The relegation of Mariology to ecclesiology at Vatican II did nothing to settle the issue.... Much of the criticism ... of the thoroughgoing communication of idioms between Mary and the Church, bears finally upon this emphasis of a Mariology then [ca. the 1960s] perceived to be old-fashioned and now perceived also to be an affront to the ecumenism taught at Vatican II. Nonetheless the Marian piety associated with the ascription of a redemptive role to the Theotokos had and has a better base than has the criticism made of it, and is far more deeply grounded in the analogy of faith than it has been given credit for by either side of the debate."
— Donald Keefe, Covenantal Theology (1991), p. 304, n. 140.