Luther yes, Calvin maybe not…there’s a lot of debate about Calvin’s development on the matter.
Most thinking Protestants do accept the doctrine that Mary is the Mother of God, though most do not accept her perpetual virginity.
This is kind of a messy broadside, Bill.
Martin Luther on Mary’s Perpetual Virginity
Christ, our Savior, was the real and natural fruit of Mary’s virginal womb . . . This was without the cooperation of a man, and she remained a virgin after that.
{Luther’s Works, eds. Jaroslav Pelikan (vols. 1-30) & Helmut T. Lehmann (vols. 31-55), St. Louis: Concordia Pub. House (vols. 1-30); Philadelphia: Fortress Press (vols. 31-55), 1955, v.22:23 / Sermons on John, chaps. 1-4 (1539) }
Christ . . . was the only Son of Mary, and the Virgin Mary bore no children besides Him . . . I am inclined to agree with those who declare that ‘brothers’ really mean ‘cousins’ here, for Holy Writ and the Jews always call cousins brothers.
{Pelikan, ibid., v.22:214-15 / Sermons on John, chaps. 1-4 (1539) }
A new lie about me is being circulated. I am supposed to have preached and written that Mary, the mother of God, was not a virgin either before or after the birth of Christ . . .
{Pelikan, ibid.,v.45:199 / That Jesus Christ was Born a Jew (1523) }
Scripture does not say or indicate that she later lost her virginity . . .
When Matthew [1:25] says that Joseph did not know Mary carnally until she had brought forth her son, it does not follow that he knew her subsequently; on the contrary, it means that he never did know her . . . This babble . . . is without justification . . . he has neither noticed nor paid any attention to either Scripture or the common idiom.
{Pelikan, ibid.,v.45:206,212-3 / That Jesus Christ was Born a Jew (1523) }
Editor Jaroslav Pelikan (Lutheran) adds:
Luther . . . does not even consider the possibility that Mary might have had other children than Jesus. This is consistent with his lifelong acceptance of the idea of the perpetual virginity of Mary.
{Pelikan, ibid.,v.22:214-5}
John Calvin on Mary’s Perpetual Virginity
Helvidius displayed excessive ignorance in concluding that Mary must have had many sons, because Christ’s ‘brothers’ are sometimes mentioned.
{Harmony of Matthew, Mark & Luke, sec. 39 (Geneva, 1562), vol. 2 / From Calvin’s Commentaries, tr. William Pringle, Grand Rapids, MI: Eerdmans, 1949, p.215; on Matthew 13:55}
[On Matt 1:25:] The inference he [Helvidius] drew from it was, that Mary remained a virgin no longer than till her first birth, and that afterwards she had other children by her husband . . . No just and well-grounded inference can be drawn from these words . . . as to what took place after the birth of Christ. He is called ‘first-born’; but it is for the sole purpose of informing us that he was born of a virgin . . . What took place afterwards the historian does not inform us . . . No man will obstinately keep up the argument, except from an extreme fondness for disputation.
{Pringle, ibid., vol. I, p. 107}
Under the word ‘brethren’ the Hebrews include all cousins and other relations, whatever may be the degree of affinity.
{Pringle, ibid., vol. I, p. 283 / Commentary on John, (7:3) }
Huldreich Zwingli
He turns, in September 1522, to a lyrical defense of the perpetual virginity of the mother of Christ . . . To deny that Mary remained ‘inviolata’ before, during and after the birth of her Son, was to doubt the omnipotence of God . . . and it was right and profitable to repeat the angelic greeting - not prayer - ‘Hail Mary’ . . . God esteemed Mary above all creatures, including the saints and angels - it was her purity, innocence and invincible faith that mankind must follow. Prayer, however, must be . . . to God alone . . .
‘Fidei expositio,’ the last pamphlet from his pen . . . There is a special insistence upon the perpetual virginity of Mary.
{G. R. Potter, Zwingli, London: Cambridge Univ. Press, 1976, pp.88-9,395 / The Perpetual Virginity of Mary . . ., Sep. 17, 1522}
Zwingli had printed in 1524 a sermon on ‘Mary, ever virgin, mother of God.’
{Thurian, ibid., p.76}
I have never thought, still less taught, or declared publicly, anything concerning the subject of the ever Virgin Mary, Mother of our salvation, which could be considered dishonourable, impious, unworthy or evil . . . I believe with all my heart according to the word of holy gospel that this pure virgin bore for us the Son of God and that she remained, in the birth and after it, a pure and unsullied virgin, for eternity.
{Thurian, ibid., p.76 / same sermon}