What is Mary's role in our salvation? Is not Jesus Christ the one mediator between God and Man?
Mary's role in our salvation can be summarized by the terms "Co-redemptrix; Mediatrix and Advocate" (see CCC No, 969). Mary's maternal role in our salvation as summarized by these titles is part of the teachings of the Church.
St Paul teaches that "there is one mediator between God and men, the man Christ Jesus, who gave Himself as a ransom for all". (1 Tim 2: 5). Mary's participation in our salvation history as Mother of Christ and Mother of Christians does not diminish the unique mediation of Christ; rather it points to Christ's unique mediation and reveals its power.
In recent years there has been an increased speculation as to whether the Church will dogmatically define Mary's role as Coredemptrix, Medatrix and Advocate. In fact, I am one of those people who are advocating that Mary Mother of Jesus should be considered for these titles. I was a signatory to a petition drive that sent a petition with 4.5 million signatories to the Holy father Pope John Paul II in 1995 for him to proclaim a new dogma of the Catholic Faith that the Blessed Virgin Mary is Coredemptrix Mediatrix and Advocate. Though the Holy Father could not do this before his death in 2005.
However, whether the Church ultimately does so or not we are required to "think with the Church" and also required to understand the rock-solid doctrine behind these titles. Some people object to these titles, particularly to Mary being considered "Coredemptrix" and "Mediatrix", because they think the titles somehow detract from Christ. But remember, just as human fathers participate in the one fatherhood of God, and priests participate in the one priesthood of Christ, so also God has chosen to associate Mary in a unique way with Christ's one mediation.
Mary's pivotal role in salvation history does not end with her giving birth to the son of God, but rather continues to the present time when we need her intercession, mediation and her continuous prayers. If we acknowledge that we can pray for each other as members of the body of Christ (e.g., 1 Thess. 5: 25, 2Thess. 1: 11), then surely we would want the prayers of the woman whom all generations call blessed (Lk 1: 48), the prayers of the woman whom the angel Gabriel said to, "Rejoice so highly favoured! The Lord is with you." (Lk. 1: 28) The woman to whom Elizabeth filled with the Holy Spirit gave a loud cry and said, "Of all women you are the most blessed and blessed is the fruit of your womb." (Lk. 1: 42) Yes, this is the woman, the Blessed Virgin Mary the Mother of God who we want all these titles to be addressed to. After all, not even death can separate the members of God's family. (Roman 8: 38