No one denies that the Bible mentions brethren of Christ, as in Mark 6:3. Such references are a real stumbling block for Protestants to believe in Mary’s perpetual virginity. Many Catholics might also suffer from such confusion, particularly in the absence of good catechesis and preaching on the Blessed Mother. While there are biblical supports, Marian teaching is an area where the importance of Sacred Tradition is proven. Our beliefs about her have been passed down from the days when she was treasured as our Lord’s most intimate living witness in the early Church. Since she was not the direct mother of the “brothers and sisters” of Jesus, she is entrusted to John at the Cross. The family of faith will take care of her and in return she will manifest a spiritual motherhood among them.
Protestants generally agree with Catholics that prior to the birth of Jesus, Mary was a virgin. The prophecy of a virgin with child in Isaiah 7:14 is fulfilled in Matthew 1:23. The scene of the annunciation confirms her virginity. The angel Gabriel tells her that she will conceive and bear a son (Luke 1:31). Mary immediately asks how this could be since she has not known man, in other words, had sexual relations. The angel makes it clear that the agency for her pregnancy would be divine power: “The Holy Spirit will come upon you, and the power of the Most High will overshadow you” (Luke 1:35).