Ecumenical dialogues that seek to bring all followers of Christ closer to unity face many difficulties. One of them is the wrong understanding of ecumenism (doctrinal, spiritual and practical). Also an obstacle is the lack of distinction between the unity of Christians and the unity of the Churches. This article undertakes the presentation of another such difficulty in the path of Christian unity, which is the Mariological (doctrinal) and Marian (worship/devotion) issues. Ecumenical meetings, therefore, do not avoid such difficult topics concerning the Mother of the Lord, such as her virginity, Immaculate Conception, Assumption or her role as Mother of the Church. Many Christian traditions have different interpretations of these truths. Catholic and Orthodox communities even consider them an inalienable part of their spiritual heritage, while most Protestant communities have a more nuanced approach and do not accept these truths as binding, but reject them. A compilation of the documents to date relating to the Mother of God proves to be a big, positive surprise. Of course, these are writings of varying degrees of validity, as they come as much from international mixed official commissions as from national bilateral bodies or local debates. Nevertheless, both their prominence and impact, as well as their quantity, make it clear that the person and action of the Mother of Jesus nevertheless animates and strengthens the difficult rapprochement of the followers of her Divine Son.