Perpetual virginity of Mary

The perpetual virginity of Mary is the doctrine that Mary, the mother of Jesus Christ, was a virgin "ante partum, in partu, et post partum"—before, during and after the birth of Christ. It is one of the four Marian dogmas of the Catholic Church, and is held also by the Eastern Orthodox Churches in Eastern Christianity and by some Lutherans and Anglicans in Western Christianity.
There is no biblical basis for the belief, which arose at the end of the 2nd century in ascetic circles who believed that sex and marriage were symptoms of original sin, and was affirmed as orthodoxy during the 4th century debates between supporters of virginity on the one hand and Christian marriage on the other.
Those debates centred on the question of whether scripture did or did not indicate that Mary had other children, for the Pauline epistles, the four canonical gospels, and the "Acts of the Apostles", all mention the brothers ("adelphoi") of Jesus; the scriptural evidence is not absolutely conclusive, but Thomas Aquinas said that although reason could not prove Mary's perpetual virginity it must be accepted because it was "fitting", for as Jesus was the only-begotten son of God, so he should also be the only-begotten son of Mary. The lack of scriptural support led to it being largely abandoned by most Protestants.
Doctrine.
The perpetual virginity of Mary is one of the four Marian dogmas of the Catholic Church, meaning that it is held to be a truth divinely revealed, the denial of which is heresy. (The other three are her role as "Theotokos" (meaning mother of God), her Immaculate Conception, and her bodily Assumption into heaven). It declares her virginity before, during and after the birth of Jesus, or in the definition formulated by Pope Martin I at the Lateran Council of 649:The blessed ever-virginal and immaculate Mary conceived, without seed, by the Holy Spirit, and without loss of integrity brought him forth, and after his birth preserved her virginity inviolate.Western Catholic and Eastern Orthodox churches both recognise Mary as "Aeiparthenos", meaning "ever-virgin". Thomas Aquinas said that reason could not prove this, but that it must be accepted because it was "fitting", for as Jesus was the only-begotten son of God, so he should also be the only-begotten son of Mary, as a second and purely human conception would disrespect the sacred state of her holy womb. The 2nd century "Gospel of James" affirms that Mary was always a virgin before, during and after childbirth, stating that Jesus' brothers (adelphos) were sons of Joseph from a previous marriage. It describes how the hand of the midwife who attempted to test the holy mother's integrity by inserting her finger into Mary's vagina burst into flames and withered. 
Symbolically, the perpetual virginity of Mary signifies a new creation and a fresh start in salvation history. It has been stated and argued repeatedly, most recently by the Second Vatican Council:
This union of the mother with the Son in the work of salvation is made manifest from the time of Christ's virginal conception … then also at the birth of Our Lord, who did not diminish his mother's virginal integrity but sanctified it... ("Lumen Gentium", No.57)
History.
Origins: 2nd century.
The exact origin of the tradition of Mary's perpetual virginity is unknown Her virginity before Jesus' birth is attested in the Gospel of Matthew and in the Gospel of Luke, but there is no biblical basis for her virginity during and after the birth. Mary's virginity, pre or post natal, seems to have attracted little theological attention prior to the end of the 2nd century, Ignatius of Antioch (c.35-108), for example, discussing it only to argue for the reality of Jesus's human birth against the docetic heretics who denied him any humanity.
The idea of Mary's perpetual virginity first appears in a late 2nd century text called the "Gospel of James" (or "Protoevangelium of James"), which is "the ultimate source of almost all later Marian doctrine." In this story Mary remains a life-long virgin, Joseph is an old man without physical desire, who marries her; the brothers of Jesus are explained as Joseph's sons by an earlier marriage. The birth takes place in a cave near Bethlehem, and the new-born Jesus simply appears from a cloud and a blinding light and takes his mother's breast; a midwife is present outside the cave, who believes, and her acquaintance Salome, who demands to touch the physical organs of the holy mother:
The midwife came out of the cave [in which the birth took place], and Salome met her. And she said to her: "Salome, Salome, I have I have a new sight to tell you; a virgin has brought forth, a thing which her nature does not allow." And Salome said: "As the Lord my God lives, unless I put (forward) my finger and test her condition, I will not believe that a virgin has brought forth." And Salome went in and made her ready to test her condition. And she cried out saying: "I have tempted the living God..." (The Protoevangelium of Gospel of James, 19:3-20, quoted in Brown, 1978). 
Salome's hand withers, but she prays to God for forgiveness and an angel appears and tells her to touch the Christ-child again, whereupon her hand is restored; the episode performs the same function as "doubting Thomas" in the Gospel of John.
James possibly derives from a sect called the Encratites, whose founder Tatian taught that sex and marriage were symptoms of original sin; its context was the growth of asceticism with its emphasis on celibacy, the monks seeing all sexual activity as tainted by sin. It was widely distributed and seems to have formed the basis of the stories of Mary in the Quran.
3rd–4th century establishment of orthodoxy.
By the third century Hippolytus held that Mary was ""all-holy Mary, ever-virgin"," in the early 4th century the spread of monasticism promoted celibacy as the ideal Christian state, and a moral hierarchy was established, with marriage occupying the third rank below life-long virginity and widowhood. Around 380 Helvidius objected to the devaluation of marriage inherent in this view and argued that the two states, of virginity and marriage, were equal; but his contemporary Jerome, realising that this would lead to the Mother of God occupying a place in heaven lower than virgins and widows, defended her perpetual virginity in his influential works "The Perpetual Virginity of Blessed Mary" and "Against Jovinianus" issued c.383.
Helvidius soon faded from the scene, but in the early 380s the monk Jovinian wrote that if Jesus did not undergo a normal human birth then he himself was not human, which was the heresy known as Manichaeism. Jerome wrote against Jovinian but failed to mention this aspect of his teaching, and most commentators believe that he did not find it offensive. The only important Christian intellectual to defend Mary's virginity "in partu" was Ambrose, Archbishop of Milan, who was the chief target of the charge of Manicheism. For Ambrose, both the physical birth of Jesus by Mary and the baptismal birthing of Christians by the Christian Church had to be totally virginal, even "in partu", in order to cancel the stain of original sin, of which the pains of labor are the physical sign. It was due to Ambrose that "virginitas in partu" came to be included consistently in the thinking of subsequent theologians.
Jovinian's view was rejected at a Synod of Milan held under Ambrose's presidency in 390, after which Mary's perpetual virginity was established as the only orthodox view. The Council of Ephesus in 431 established a full general consensus on the subject, in 553 the Second Council of Constantinople gave her the title "Aeiparthenos", meaning Perpetual Virgin, and at the Lateran Council of 649 Pope Martin I emphasised its threefold character, before, during, and after the birth of Christ.
Protestant Reformation.
The Protestant Reformation rejected the sanctity of virginity, and as a result marriage and parenthood were extolled, Mary and Joseph were seen as a normal married couple, and sexual abstinence was no longer regarded as a virtue. It also brought the idea of the Bible as the fundamental source of authority regarding God's word "(sola scriptura)", and the reformers noted that while holy scripture explicitly required belief in the virgin birth, it only permitted acceptance of perpetual virginity. But despite the lack of a clear biblical basis for the doctrine, it was supported by Martin Luther (who included it in the Smalcald Articles, a Lutheran confession of faith written in 1537) as well as by Huldrych Zwingli, John Calvin, and later John Wesley, the co-founder of Methodism. This was because these moderate reformers were under pressure from others more radical than themselves who held Jesus to have been no more than a prophet: Mary's perpetual virginity thus became a guarantee of the Incarnation, despite its shaky scriptural foundations. Notwithstanding this early acceptance by the reformers, modern Protestants, apart from some Lutherans and Anglo-Catholics, have largely rejected the perpetual virginity and it has rarely appeared explicitly in confessions or doctrinal statements.
Arguments and evidence.
The problem facing theologians who wanted to maintain Mary's perpetual virginity is that the New Testament mentions the brothers ("adelphoi") of Jesus, with Mark and Matthew recording their names and Mark adding unnamed sisters, and her virginity is explicitly affirmed only prior to the conception of Jesus. The 2nd century "Gospel of James" states the "adelphoi" were Joseph's children by an earlier marriage, which is still the view of the Orthodox Christian churches. Jerome believed that Joseph, like Mary, must have been a life-long virgin, and said that they were the sons of a different Mary entirely, a kinswoman of the Virgin; a modern variation is that the second Mary, mentioned in as the wife of Clopas, was not a kinswoman of Mary's but that Clopas was Joseph's brother, but the word "adelphos" only very rarely carries any other meaning than a physical or spiritual sibling.
Further scriptural difficulties were added by , which calls Jesus the "first-born" son of Mary, and , which adds that Joseph did not "know" (consummated marriage) his wife "until she had brought forth her firstborn son." Helvidius argued that first-born implies later births, and that the word "until" left open the way to sexual relations after the birth; Jerome, replying that even an only son will be a first-born, and that "until" did not have the meaning Helvidius construed for it, painted a repulsive word-portrait of Joseph having intercourse with a blood-stained and exhausted Mary immediately after she has given birth - the implication, in his view, of Helvidius's arguments. Opinions on the quality of Jerome's rebuttal range from the view that it was masterful and well-argued to thin, rhetorical and sometimes tasteless.
Two other 4th century Fathers, Gregory of Nyssa and Augustine, advanced a further argument by reading as a vow of perpetual virginity on Mary's part, although virginity was never an ideal in Israel and such a vow would have been "inconceivable" among Jews of the time. Nevertheless, this argument, and those advanced by Jerome and Ambrose, were put forward by Pope John Paul II in his catechesis of August 28, 1996, as the four facts supporting the Catholic Church's ongoing faith in Mary's perpetual virginity:
...[T]here are no reasons for thinking that the will to remain a virgin, which Mary expressed at the moment of the Annunciation (cf. Luke 1:34) was then changed. Moreover, the immediate meaning of the words "Woman, behold your son!" "Behold your mother" (John 19:26), which Jesus addressed from the Cross to Mary and his favorite disciple, imply that Mary had no other children.
...[T]he word "firstborn" literally means "a child not preceded by another", and, in itself, makes no reference to the existence of other children.
...The phrase "brothers of Jesus" indicates "the children" of a Mary who was a disciple of Christ (cf. Matthew 27:56) and who is significantly described as "the other Mary" (Matthew 28:1). "They are close relations of Jesus, according to an Old Testament expression."