The tradition of Mary's role in the early Church dates back to the first centuries. The only biblical text that treats the literal meaning of this topic is Acts 1:14, which describes the Eleven apostles in the Upper Room after Jesus’ Ascension: "With one heart all these joined constantly in prayer, together with some women, including Mary, the mother of Jesus, and with his brothers" (Acts 1:14).
This passage gets our attention and invites us to think and meditate. Luke notes Mary’s presence in the early Church, and at the same time he arouses our curiosity by telling us almost nothing about her: almost nothing, but not absolutely nothing. By mentioning Mary’s presence among those waiting for the Spirit "to come" upon them and fill them with its "power" (Acts 1:8), he reminds us of the scene of the Annunciation, when the angel told Mary: "The Holy Spirit will come upon you, and the power of the Most High will cover you with its shadow" (Lk 1:35).
We are encouraged to see that the Church about to be born will continue the earthly existence of Mary’s Child. In his gospel, Saint Luke shows Mary taking care of her newborn Baby and watching over Him throughout His childhood. In Acts 1:14, he invites us to think that Mary also took care of the newborn Church. Luke gives us another clue by the very manner in which he wrote Act 1:14: "With one heart (the apostles)… together with some women, including Mary…and with his brothers.”
Luke sees Mary as a central figure, a Mediatrix, in the early Church
Note the term "and" is repeated, before and after mentioning Mary. The "and" links her, on one side, to the Apostles and "some women" (presumably those who accompanied the group of the Apostles; cf. Lk 8:7-3) and on the other side to Jesus’ brothers. But those two poles, the Apostles and women believers on the one hand, and Jesus’ close male relatives on the other, are far from being similar in the Gospels, although Luke does not emphasize the contrast between them as strongly as do Mark (3:21) and John (7:5). In the Acts, the very sentence structure (1:14) makes Mary Mediatrix between the two extremes. This role of mediation has already been prepared in the third Gospel. Here, Mary belongs to both groups: by blood, of course, she belongs to Jesus’ natural family, but by faith she belongs to His new family (Lk 8:19-21).
The presence of Jesus’ brothers in the Upper Room tells us that they have learned to believe in Christ (cf. 1 Cor 15:7) and are in communion with His disciples. The way in which Mary is placed between the two groups suggests that she is the one who kept them all together. It seems reasonable to infer that Luke sees Mary as a central figure, a Mediatrix, in the early Church, and he was well aware that that Body consisted of various and possibly even rival groups.