It seems that Martin Luther and John Calvin had some surprisingly Catholic viewpoints. Martin Luther had this to say regarding Mother Mary:
Mary is the Mother of Jesus And the Mother of us all...
If He is ours, we ought to be in his situation; there where he is, we ought also to be and all that he has ought to be ours, and his mother is also our mother.
Our prayers should include the Mother of God....What the Hail Mary says is that all glory should be given to God, using these words: "Hail Mary, full of grace. The Lord is with thee; blessed art thou amongst women and blessed is the fruit of thy womb, Jesus Christ. Amen! You see that these words are not concerned with prayer, but purely with giving praise and honor....We can use the Hail Mary as a meditation in which we recite what grace God has given her. Second, we should add a wish that everyone may know and respect her...He who has no faith is advised to refrain from saying the Hail Mary....
Although she was without sin , yet that grace was far too great for her to deserve it in any way. How should a creature deserve to become the Mother of God? ....It is necessary also to keep within bounds and not to make too much of calling her "Queen of Heaven," which is a true-enough name.... M. Luther
Sounds to me as if Martin Luther prayed the Rosary! Next is a comment by John Calvin:
We cannot give praise for the blessing which Christ has given to us without remembering at the same time the glorious privilege which God bestowed on Mary by choosing her to be the mother of his only Son....Now she is called Blessed because, receiving by faith the blessing which is offered to her, she opened the way for God to accomplish his work.
Let us learn to praise the holy Virgin. When we confess with her that we are nothing...and that we owe all to the pure goodness of God, see how we will be disciples of the Virgin Mary?