The Revised Standard Bible caused a controversy when it translated Isaiah 7:14 using the phrase "young woman" instead of "virgin", and this was believed to be a covert attack on the Virgin Birth, and to this day, many Evangelicals refuse to use the RSV or the NRSV bibles because of this verse alone. Raymond E. Brown said that Isaiah 7:14 has become a litmus tests for bible translations, such that any bible that does not translate Isaiah 7:14 with the word "virgin" is suspect and this is a tragedy for many reasons. The first is that academic theology primarily uses the NRSV for English translations and has caused Evangelicals to distrust any theologian who uses NRSV (or RSV) and therefore has caused evangelicals to distance themselves from credible theology. The second is that this litmus tests indicates that evangelicals prefer bible translations that are biased towards their ideologies. All bible translations are ultimately commentaries upon the original sources, so none are free from bias (and this is unavoidable), however it is deceptive to intentionally translate a bible contrary to its sources to make it align with one's own agendas, especially when biased bibles are toted as the only correct translation and used for subversive measures to attack those who do not use a specific english translation. Using Isaiah 7:14 as a litmus test for rejecting the RSV, NRSV, NJB or any bible translation that uses the phrase "young women" instead of "virgin" may be symptomatic of a cultic and biased approach to theology and the bible. 

In The Virginal Conception and Bodily Resurrection of Jesus, Raymond E. Brown explains that Isaiah 7:14 has become a biblical litmus test for orthodoxy, such that any English bible that does not say Isaiah 7:14 is suspect, as well as any church, theologian or Christian who prefers the NRSV, RSV, or NJB is wolf in sheep's clothing:

In Protestantism the question of the virginal conception has been debated for a long time. In some quarters it has been settled with a negative response about historicity, a response occasionally accompanied with a perceptive hesitancy that the negation threatens a symbolism touching on the mystery of Christ. In other quarters an affirmative answer remains one of the essential criteria of orthodoxy, so that English Bibles which do not carry the word "virgin' in Isa 7:14 are suspect. In still other quarters the subject is discreetly avoided, except perhaps by a nervous examination board testing a candidate's doctrinal suitability for the ministry. since the denial of the virginal conception was initiated by the rationalists, there remains a certain suspicion about those who hesitate to evaluate it as a historical fact. And so it may well be that a reconsidering of the evidence will be of utility in the broad span of Protestantism. [1]

Raymond E. Brown argues that "young woman" is the correct translation of Isaiah 7:14, because the Hebrew manuscripts for this verse use the word for "young woman" and not "virgin". When the Hebrew bible was translated into Greek (i.e. Septuagint / LXX), the Greek translators chose the term "virgin" (παρθένος) to represent the Hebrew word for "young woman" (`almah), and this changed the meaning of Isaiah 7:14 from "young woman" to "virgin". The New Testament was written in Greek, and used the Greek translation of the Hebrew Bible when citing the Old Testament. When the New Testament writers saw the word "virgin" in the Septuagint supported the Virgin Birth, the Greek translation was cited (c.f. Matt 1:23; Luke 1:31,34). Brown argues that Isaiah was written 700 years before the New Testament, and so Isaiah knew nothing about the Virgin Birth. Only after the New Testament writers cited the Greek translation of Isaiah 7:14, did that verse take on new meaning, and was then used to support the Virgin Birth. Brown says a similar situation has happened in Hosea, and Hosea 6:2 read in isolation within its original context, it does not communicate anything about the duration of Jesus in the tomb, and it gained this meaning, only after the authors of the New Testament employed it in their writings. 

The OT authors did not foresee in detail the life of Jesus of Nazareth. Those who are called OT prophets were concerned with their own times and not with the distant future about which they could speak only in the vaguest way. Therefore, whether they know it or not, when the NT authors see prophecy fulfilled in Jesus, they are going beyond the vision of the OT authors [footnote #12: "The classic apologetic argument from prophecy has had to be reinterpreted in the light of modern biblical criticism. It is no longer primarily a question of the exact fulfillment of divinely guided foreknowledge; it is much more a question of the culmination of a divine plan that could only be detected through hindsight."].

Let us take, for instance, Isa 7:14: "A young woman shall be [or is] with child and shall bear a son and shall call him Immanuel." The prophet was referring to the birth of a child taking place some seven hundred years before Jesus' time, a child whose coming into the world was a sign of the continuance of the royal Davidic line. Because Matthew regarded Jesus as the completion of the royal Davidic line, and because he read the passage in a Greek translation of Isaiah which spoke of a "virgin" (as distinct from the Hebrew which has only "young woman"), Matthew saw the applicability of this text to the birth of Jesus from the Virgin Mary at Bethlehem. It was a proof for Matthew who had an insight as to how Jesus' birth fulfilled God's plan; but, so far as we can tell, Isaiah knew nothing or foresaw nothing about Jesus' birth. Similarly, Hosea 6:2, "After two days he will revive us; on the third day he will raise us up," in the prophet's mind had nothing to do with the resurrection of Jesus. The likeness to the NT theme of the resurrection of Jesus on the third day (1 Cor 15:4) may have arisen because the NT authors deliberately phrased their remembrance of the resurrection in the language of Hosea. [2]

Raymond E. Brown makes a very important point that regardless of whether Isaiah 7:14 is translated with the phrase "young woman" or "virgin", neither of these terms fundamentally prove that Isaiah 7:14 knew anything about the Virgin Birth. If Isaiah 7:14 is translated as "virgin", this may simply mean that the woman was a virgin before she conceived, and does not teach anything about an immaculate conception or perpetual virginity of Mary.  

Hellenistic Judaism has seemed a more fertile field for search because Matthew makes reference to the Greek (LXX) text of Isa 7:14, "The virgin shall conceive." But we have no evidence that in Alexandria Judaism the LXX of Isa 7:14 was understood to predict a virginal conception, since it need mean no more than that the girl who is now a virgin will ultimately conceive (in a natural way). Moreover, it is dubious that Isa 7:14 played any major role in shaping the Lucan account of the virginal conception. [3]

Translations of Isaiah 7:14

• New Revised Standard Bible (Isaiah 7:14 RSV): "Therefore the Lord himself will give you a sign. Look, the young woman is with child and shall bear a son, and shall name him Immanuel."
• Revised Standard Bible (Isaiah 7:14 RSV): "Therefore the Lord himself will give you a sign. Behold, a young woman shall conceive and bear a son, and shall call his name Imman′u-el."
• New Jerusalem Bible (Isaiah 7:14 NJB): "The Lord will give you a sign in any case: It is this: the young woman is with child and will give birth to a son whom she will call Immanuel."
• New International Version (Isaiah 7:14 NIV): "Therefore the Lord himself will give you a sign: The virgin will conceive and give birth to a son, and will call him Immanuel."
• King James Version (Isaiah 7:14 KJV): "Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel."
• English Standard Version (Isaiah 7:14 ESV): "Therefore the Lord himself will give you a sign. Behold, the virgin shall conceive and bear a son, and shall call his name Immanuel." 

Sources:

1. Raymond E. Brown, The Virginal Conception and Bodily Resurrection of Jesus, Chapman, 1974. p. 22
2. Ibid. pp. 15-16.
3. Ibid. p. 64.