Alright. What Biblical inferences draw your way to show that Mary was a perpetual virgin? A few times BD has given a list of scriptures showing that Jesus had siblings. What scriptures do you offer to show that He did not? It would seem that your best possible argument, one in which every single verse was interpreted exactly as you needed, would be that the Bible is silent on the matter. Nothing that is actually in the Bible really helps you here. The Marian doctrines are (mostly) completely extra-scriptural. That is why our side is the only one that actually HAS Biblical inferences. All your side can do is interpret some verses out of meaningful existence, and then rely solely on extra-scriptural text for the "facts".
Here, Sola Scriptura makes a strong case against Mary's perpetual virginity. If your refutation was based on other scripture, then you would have a case. But it does not appear to be. It appears that it is only based on re-interpreting the "positive" argument in scripture out of existence, and then using only extra-scriptural text to support an alternative "positive" argument. I would imagine that an unbiased observer would find this very unpersuasive if a premise was that scripture was an equal authority. Sola Scriptura is only dangerous to the RCC. :)
It makes a case. Not a strong case. The "brothers" reference melts down if you look at all references to "brothers" in the expansive sense. The purification is simply a ritual providing for natural births that Mary followed, and the Evangelist point out that is was just that.
On the other hand, we have an absolute scriptural case for virgin conception, and extrapolate from there. If a child can be conceived by God without an intercourse, He certainly can be birthed without violating the hymen. Marital relations for Mary, as we discussed many times, would not have been a sin, but simply make no sense for Mary in her state of sanctification.
But for the purposes of this conversation I will grant you that from the Sola Scriptura perspective there is (1) a case for Mary giving a natural birth and having marital relations, there is (2) a case that the scripture is silent, and there is no positive case for perpetual virginity in every sense of the word. So? Sola Scriptura is a wrong proposition. Start from it, and you get nowhere fast, as the Protestant experience demonstrates.
Martin Luther (1483-1546):
It is an article of faith that Mary is Mother of the Lord and still a virgin. ... Christ, we believe, came forth from a womb left perfectly intact.
(Weimer's The Works of Luther, English translation by Pelikan, Concordia, St. Louis, v. 11, pp. 319-320; v. 6. p. 510.)
" This immaculate and perpetual virginity forms, therefore, the just theme of our eulogy. Such was the work of the Holy Ghost, who at the Conception and birth of the Son so favoured the Virgin Mother as to impart to her fecundity while preserving inviolate her perpetual virginity."9
In this work whereby she was made the Mother of God, so many and such great good things were given her that no one can grasp them. ... Not only was Mary the mother of him who is born [in Bethlehem], but of him who, before the world, was eternally born of the Father, from a Mother in time and at the same time man and God.
(Weimer's The Works of Luther, English translation by Pelikan, Concordia, St. Louis, v. 7, p. 572.)
The French reformer John Calvin (1509-1564):
It cannot be denied that God in choosing and destining Mary to be the Mother of his Son, granted her the highest honor. ... Elizabeth called Mary Mother of the Lord, because the unity of the person in the two natures of Christ was such that she could have said that the mortal man engendered in the womb of Mary as at the same time the eternal God.
(Calvini Opera, Corpus Reformatorum, Braunschweig-Berlin, 1863-1900, v. 45, p. 348, 35.)
The Swiss reformer, Ulrich Zwingli (1484-1531), wrote:
I firmly believe that Mary, according to the words of the gospel as a pure Virgin brought forth for us the Son of God and in childbirth and after childbirth forever remained a pure, intact Virgin.
(Zwingli Opera, Corpus Reformatorum, Berlin, 1905, v. 1, p. 424.)
The Bible:
In the Bible, it is obvious that Virgin Mary was always Virgin, and she only had one child: Jesus Christ, our Savior.
1- At Calvary:
It is obvious that Jesus did not have any other brothers nor sisters, because at Calvary He had to entrust His Mother to a friend, to John, " and from that moment the disciple took her to his own home" (Jn.19:27).
It would be unthinkable for a Jewish mother to go to live with a friend after the death of her son, if she had any other child of her own!...
* I find it intersting so many in here think themselves more knowledgeable than the vast vast asembly of Christians born before them who went to their graves convinced of the perpetual virgintiy of Mary. Saints, Popes, Ecumenical Councils, even the Progenitors of the Protestant Reformation are all wrong.
If everyone else who has ever lived is wrong and only you are right, what might that reveal about your ideas?