General Whatever may be the position theologically that one may take today on the subject of Mariology, one is not able to call to one's aid 'reformed tradition' unless one does it with the greatest care . . . the Marian doctrine of the Reformers is consonant with the great tradition of the Church in all the essentials and with that of the Fathers of the first centuries in particular . . . . .
In regard to the Marian doctrine of the Reformers, we have already seen how unanimous they are in all that concerns Mary's holiness and perpetual virginity . . .
{Max Thurian (Protestant), Mary: Mother of all Christians, tr. Neville B. Cryer, NY: Herder & Herder, 1963 (orig. 1962), pp. 77, 197}
The title 'Ever Virgin' (aeiparthenos, semper virgo) arose early in Christianity . . . It was a stock phrase in the Middle Ages and continued to be used in Protestant confessional writings (Luther, Calvin, Zwingli, Andrewes; Book of Concord [1580], Schmalkaldic Articles [1537]).
{Raymond E. Brown et al, ed., Mary in the New Testament, Phil.: Fortress Press / NY: Paulist Press, 1978, p.65 (a joint Catholic-Protestant effort) }
Mary was formally separated from Protestant worship and prayer in the 16th century; in the 20th century the divorce is complete. Even the singing of the 'Magnificat' caused the Puritans to have scruples, and if they gave up the Apostles' Creed, it was not only because of the offensive adjective 'Catholic', but also because of the mention of the Virgin . . .
[But] Calvin, like Luther and Zwingli, taught the perpetual virginity of Mary. The early Reformers even applied, though with some reticence, the title Theotokos to Mary . . . Calvin called on his followers to venerate and praise her as the teacher who instructs them in her Son's commands.
{J.A. Ross MacKenzie (Protestant), in Stacpoole, Alberic, ed., Mary's Place in Christian Dialogue, Wilton, Conn.: Morehouse-Barlow, 1982, pp.35-6}