Most Protestants claim that Mary bore children other than Jesus. To support their claim, these Protestants refer to the biblical passages which mention the "brethren of the Lord." As explained in the Catholic Answers tract Brethren of the Lord, neither the Gospel accounts nor the early Christians attest to the notion that Mary bore other children besides Jesus. The faithful knew, through the witness of Scripture and Tradition, that Jesus was Mary’s only child and that she remained a lifelong virgin.1
An important historical document which supports the teaching of Mary’s perpetual virginity is the Protoevangelium of James, which was written probably less than sixty years after the conclusion of Mary’s earthly life (around A.D. 120), when memories of her life were still vivid in the minds of many. According to the world-renowned patristic scholar, Johannes Quasten, "The principal aim of the whole writing [Protoevangelium of James] is to prove the perpetual and inviolate virginity of Mary before, in, and after the birth of Christ" (Patrology, 1:120–1).
To begin with, the Protoevangelium records that when Mary’s birth was prophesied, her mother, St. Anne, vowed that she would devote the child to the service of the Lord, as Samuel had been by his mother (1 Sam. 1:11). Mary would thus serve the Lord at the Temple, as women had for centuries (1 Sam. 2:22), and as Anna the prophetess did at the time of Jesus’ birth (Luke 2:36–37). A life of continual, devoted service to the Lord at the Temple meant that Mary would not be able to live the ordinary life of a child-rearing mother. Rather, she was vowed to a life of perpetual virginity.
However, due to considerations of ceremonial cleanliness, it was eventually necessary for Mary, a consecrated "virgin of the Lord," to have a guardian or protector who would respect her vow of virginity. Thus, according to the Protoevangelium, Joseph, an elderly widower who already had children, was chosen to be her spouse. (This would also explain why Joseph was apparently dead by the time of Jesus’ adult ministry, since he does not appear during it in the gospels, and since Mary is entrusted to John, rather than to her husband Joseph, at the crucifixion).
According to the Protoevangelium, Joseph was required to regard Mary’s vow of virginity with the utmost respect. The gravity of his responsibility as the guardian of a virgin was indicated by the fact that, when she was discovered to be with child, he had to answer to the Temple authorities, who thought him guilty of defiling a virgin of the Lord. Mary was also accused of having forsaken the Lord by breaking her vow. Keeping this in mind, it is an incredible insult to the Blessed Virgin to say that she broke her vow by bearing children other than her Lord and God, who was conceived through the power of the Holy Spirit.
The perpetual virginity of Mary has always been reconciled with the biblical references to Christ’s brethren through a proper understanding of the meaning of the term "brethren." The understanding that the brethren of the Lord were Jesus’ stepbrothers (children of Joseph) rather than half-brothers (children of Mary) was the most common one until the time of Jerome (fourth century). It was Jerome who introduced the possibility that Christ’s brethren were actually his cousins, since in Jewish idiom cousins were also referred to as "brethren." The Catholic Church allows the faithful to hold either view, since both are compatible with the reality of Mary’s perpetual virginity.
Today most Protestants are unaware of these early beliefs regarding Mary’s virginity and the proper interpretation of "the brethren of the Lord." And yet, the Protestant Reformers themselves—Martin Luther, John Calvin, and Ulrich Zwingli—honored the perpetual virginity of Mary and recognized it as the teaching of the Bible, as have other, more modern Protestants.
The Protoevangelium of James - "And behold, an angel of the Lord stood by [St. Anne], saying, ‘Anne! Anne! The Lord has heard your prayer, and you shall conceive and shall bring forth, and your seed shall be spoken of in all the world.’ And Anne said, ‘As the Lord my God lives, if I beget either male or female, I will bring it as a gift to the Lord my God, and it shall minister to him in the holy things all the days of its life.’ . . . And [from the time she was three] Mary was in the temple of the Lord as if she were a dove that dwelt there" (Protoevangelium of James 4, 7 [A.D. 120]).
"And when she was twelve years old there was held a council of priests, saying, ‘Behold, Mary has reached the age of twelve years in the temple of the Lord. What then shall we do with her, lest perchance she defile the sanctuary of the Lord?’ And they said to the high priest, ‘You stand by the altar of the Lord; go in and pray concerning her, and whatever the Lord shall manifest to you, that also will we do.’ . . . [And] he prayed concerning her, and behold, an angel of the Lord stood by him saying, ‘Zechariah! Zechariah! Go out and assemble the widowers of the people and let them bring each his rod, and to whomsoever the Lord shall show a sign, his wife shall she be. . . . And Joseph [was chosen]. . . . And the priest said to Joseph, ‘You have been chosen by lot to take into your keeping the Virgin of the Lord.’ But Joseph refused, saying, ‘I have children, and I am an old man, and she is a young girl’" (ibid, 8–9).
"And Annas the scribe came to him [Joseph] . . . and saw that Mary was with child. And he ran away to the priest and said to him, ‘Joseph, whom you did vouch for, has committed a grievous crime.’ And the priest said, ‘How so?’ And he said, ‘He has defiled the virgin whom he received out of the temple of the Lord and has married her by stealth’" (ibid, 15)."And the priest said, ‘Mary, why have you done this? And why have you brought your soul low and forgotten the Lord your God?’ . . . And she wept bitterly saying, ‘As the Lord my God lives, I am pure before him, and know not man’" (ibid.).
NIHIL OBSTAT: I have concluded that the materials presented in this work are free of doctrinal or moral errors. Bernadeane Carr, STL, Censor Librorum, August 10, 2004
IMPRIMATUR: In accord with 1983 CIC 827 permission to publish this work is hereby granted. +Robert H. Brom, Bishop of San Diego, August 10, 2004
1 Catholic Answers: http://www.catholic.com/tracts/mary-ever-virgin.