Dear Thomas,
I fully recognize the kind intent of your post. But just to register that such is a prayer that I shall never offer because I think it comes dangerously close to making an idol of the most holy Theotokos. Not, holy Mary, but her SON is the hope of us Christians, one and all, and He, who is our Shepherd, will indeed guard, shelter, and protect those who put their trust in Him. It seems odd, thinking of Christian unity, to highlight a prayer in which so many of us cannot join!
In Loehe’s Seed Grains, he provided the 16th century Lutheran reworking of one of the traditional Marian Antiphons (Salve Regina), and I would think THIS is a prayer that we can all join in together (though, of course, the greatest such is the Our Father, which does indeed truly unite the children of God in their petitions!):
All hail! King of mercy. Hail! Thou who art the life, the joy and the hope of our souls. We miserable children of Eve cry unto Thee. We long for Thee, sorrowful and weeping in this vale of tears. Hail, therefore, O Lord Christ! Thou who dost intercede for us with God, turn Thine eyes, beaming with mercy upon us and show Thyself unto us, Thou blessed Son of God and of Mary, when the days of our misery shall have passed. O gracious, gentle, sweet and lovely Jesus Christ. Amen. (P. 118)