The background - Jerusalem attacked by Israel with Syria vv 1 - 2
v1  The northern 10 tribes called "Israel" joined forces with the gentile kingdom of Syria to attack Jerusalem, which was the capital of the kingdom of Judah. This was terrible. Judah was not strong enough to defend against these 2 kingdoms joined together.

v2  Their hearts wavered this way and that, not knowing what to do.

The LORD sends Isaiah to meet Ahaz vv 3 - 6
v3  Why did God tell Isaiah to bring Shearjashub his son? The main reason is because his name means "a remnant will return (or turn)". A remnant will return from where and to what? There is no illusion to the Babylonian captivity in this passage (chs 7-10). The remnant must be those who believe in Immanuel and thus return to God (10:21). This fortells that most of Israel will not accept the message that Isaiah is delivering. The message is that Immanuel will come.

Another reason for Shearjashub being there is to add the gentleness (8:6) of the message of Immanuel. The waters of Shiloah that flow gently in 8:6, which the people refused, are the very waters here at the conduit of the upper pool (Neh 3:15) (B. Newton). The gentle waters of Shiloah, which means "the sent", signify Immanuel, the Sent One. This will be covered more when we get to 8:6.

The meeting place of Isaiah, Shearjashub and Ahaz is the exact same meeting place, described with the same words even, as where Rabshakeh, sent from the king of Assyria, spoke to Hezekiah, blaspheming God (Isa 36:2; 2 Kg 18:17). I think this caused Hezekiah to remember the prophecy of Immanuel by Isaiah in the very same place, and strengthened Hezekiah to trust in the Lord.

The Hebrew word for "pool" is bracha, which also means "blessing". The Hebrew word for "upper" is alyon, which also means "Most High". The conduit is a channel, and a "fuller" is someone who washes clothes.  All these same exact words are used in Isa 36:2 & 2 Kg 18:17, so they must be significant. F. C. Jennings has rich sharing on this.

v4  The Lord has such low regard for Pekah king of Israel that He refuses to say his name, but calls him the son of Remaliah.

v6  Tabel means either "good for nothing". The person naming him may have intended for the name to mean "good is God", but in Hebrew the adjective comes after the word modified. This person, like the son of Remaliah, was so despised by God that He would not say his name, but called him the son of Tabeal.

The Lord's promise to deliver vv 7-9
v8  - Ephraim was the leading tribe of the northern kingdom of Israel, the location of the capital and the tribe of at least their first kings. Ephraim thought they were smart to join with a gentile king against Judah, but soon they would no longer be a people.

This is a judgment on Ephraim, but not an answer to Judah's dilemma because 65 years is too long to wait when you are in an emergency.

65 years - This was the 1st, 2nd or 3rd yr of Ahaz. It could not have been earlier because Ahaz was King. It could not have been later than the 3rd yr of Ahaz because Pekah  was still king (2Ki 15:27; 16:1). So at most there would be 21 years till the captivity of the northern 10 tribes: 3 yrs of Pekah, 9 years of no king, 9 years of Hoshea (2Ki 17:1,6). That means Ephraim remained as a people approx. 45 years into captivity, but then were no more a people. I think this means that after ~45 years of captivity, the distinction of Ephraim from the other 9 captive tribes was lost.
This differs from Ezekielís 390 years (Eze 4:4-5,9-13). The 390 yrs is the time that the northern kingdom ate small amounts of good food mixed with generous parts of human dung. This began with Jereboam mixing a little bit of the Torah with a lot of man-made religion and ended when Judah went into captivity to join them, at which time those who had not assimilated to be gentiles became part of Judah.

v9  - The Lord tells all His people ("you" is plural) that the way for them to be established is to have faith.

Ahaz Refuses to Ask for a Sign vv 10 - 13
v11  - Ahaz was newly king. God wanted to give him a chance to strengthen his faith.

v12  - Ahaz did not want a sign because he did not want to trust in God. He was already planning to pay the king of Assyria to attack Israel and Syria (2Ki 16:5-9).

 v13 - Ahaz knows he is lying to manís face. You also do this to God?

The previous words of the Lord thru Isaiah were rehearsed. The Lord told Isaiah to speak these words to Ahaz. Now with v13, the Lord is speaking instantly thru Isaiah.

The Promise of Immanuel v14 
v14 - There is much to say on this verse, so I have organized it as follows so you can skip the parts you are not interested in.
"They shall call" or "She shall call"
The Sign
Double-Prophecy not possible
The virgin
definate article - the virgin
usage of almah in OT
in Song of Songs
Prov 30:19 - the way of a mighty man with an almah
words close in meaning
male form, alam
naarah, young unmarried woman
betulah, virtuous woman

"They shall call" or "She shall call" 
Translations of Isaiah 7:14 from the Masoretic Hebrew Text (MT), which is the text accepted by most Jews, use the definite pronoun "she", meaning that Immanuel's mother would call her child's name Immanuel. But Matthew 1:23 uses the indefinite pronoun, "they", which means that many unspecified individuals would call his name Immanuel. This may seem like picking hairs, but it is not. Every word of the Bible must fit an interpretation just like a piece of a jigsaw puzzle. I am glad that Rabbi Tovia Singer pointed this out in his counter-missionary tapes, because it is the right way to read the Bible, and also because it gives me the ground to judge his explanations using the same criteria. Singer claims that Matthew had a very poor understanding of Hebrew and that Matthew shamelessly changed the text. Singer says that there is a big difference between the mother calling his name Immanuel and many unspecified individuals calling his name Immanuel. For the mother to name him Immanuel is a normal naming of a child. She most likely named him Immanuel because she realized that God is with us, the Jewish people, at that time.  However, according to Singer, Matthew, shamelessly changed the verse to say, "they shall call". The statement, "They shall call His name Immanuel", means not that Immanuel is His actual name, but that is what many unspecified individuals will know Him to be. The child to be born really is "God with us".

This is not a problem of translation, but a problem in the MT text. There used to be a number of manuscripts of the Old Testament text with minor variations. Just like today there are several thousand manuscripts of the New Testament text.  Around the year 200 A.D. the Jews held a council and decided on one version of the Hebrew Text, which became the Masoretic Text. The other variants were lost.
Now, just since ~1999, the text of the Dead Sea Scrolls (DSS) has been made public. This is a text of the Old Testament from ~100 B.C. The earliest copies we have from the MT are from 800+ A.D. Scholars thought that it would be impossible for the DSS to match the MT, being that there are 1000 years between them. The amazing thing is that almost every word matched from the DSS to the MT.  Almost the only difference was in the spelling of some words. The DSS contains a perfectly preserved copy of the book of Isaiah, and some other copies of Isaiah as well.  What does the DSS say for Isaiah 7:14? The DSS says literally, "he shall call", 3rd person indefinite, which DSS translators translated as "his name shall be called", which is better English, but loses some of the meaning. The best translation, which preserves that it is many unspecified individuals who call His name Immanuel, is Matthew's which says, "they shall call his name Immanuel."

I translated the indefinite pronoun "they" as "people" because the next verse continues the use of the indefinite pronoun, and if I used "they", then the "they" in v14 would be the antecedant of "they" in v15, which is not required.

The MT actually does not say, "she shall call", but says "you (fem singular) shall call", which does not make sense because there is no woman there. Because this does not make sense, all translators of the MT translate it as "she shall call", which is actually to consider that the MT text is in error.
(There are a few examples of the 2fs suffix used for 3fs: De 32:36; Isa 23:15; Eze 46:17; Jer 44:23. Jer 44:23 uses the same verb as here. I think these are scribal errors.)

The Septuagint (LXX)  which was a Jewish translation of the Old Testament into Greek done in ~100 B.C. says, "Behold, the virgin shall be with child, and shall bring forth a son, and you (singular)  shall call his name Immanuel. This shows that the LXX translated from the same Hebrew text as the MT today, so this error in the MT did not come in due to anti-Christian bias. I think the error came in due to a bias to protect the divinity of God. How could a human child actually be "God with us"?  However the Bible is written redundantly so that there are 2 or 3 witnesses to anything important. Everything in Isa 7:14-16 is repeated in more detail later in this same prophecy. Isa 9:6 tells us that this same child is the mighty God and the Father of eternity.

The Sign 
The virgin bearing a son is not the sign to Ahaz. It is the reason that the Lord will preserve Judah (Isa 8:10). The Lord must preserve Judah so that the virgin will be able to bring forth a son. The sign is the next verse.

Double prophecy? 
This cannot be a double prophecy. "The virgin is pregnant" means that she is pregnant while in the state of virginity.

The word LORD is Adonai in the MT (Masoretic Hebrew Text) and Jehovah in DSS (Dead Sea Scrolls). I think the DSS is correct because the MT scribes were used to vocalizing Jehovah as Adonai, so they could make this mistake.

The Virgin 
definate article
Virgin has the definite article "the" because it is a particular woman who has been prophesied before in Gen 3:15 & 4:1. Matthew 1:23 also used the definite article in Greek.

usage of almah in Old Testament 
Rabbi Singer's most important argument is that the Hebrew word here translated "virgin" does not mean "virgin", but just "young woman, married or unmarried".  The Hebrew word is almah. Singer starts by giving a supposedly gross example of Christian mistranslation of the Old Testament (Ps 22:16), and says that this is a basic principle of Christians showing Christ in the Old Testament. This prepares the biblically ignorant listener to believe that almah is mistranslated without looking too carefully at Singer's argument regarding almah. Then Singer says, Now let us look at another favorite verse of Christians, Isaiah 7:14. "Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel."  There's only one problem here. The word that is translated "virgin" here is never translated as "virgin" anywhere else. (audience laughs).

almah in Song of Songs 
First off, Mr. Singer, apparently misspoke on purpose. His statement, "The word that is translated 'virgin' here is never translated as 'virgin' anywhere else" is wrong. I do not know of any translation that translated almah in Isaiah 7:14 as 'virgin', but did not translate it as 'virgin' in other places, especially in Song of Songs.  Certainly not the King James Version, which Singer quoted.  In fact, the opposite is true: the top rabbi Rashi (~1000 A.D.) translated almah as virgin in Song of Songs in the Old Testament, but translated it as "young woman" in Isaiah 7:14 because he had an anti-Christian bias.  Try substituting "young women" for "virgins" in Song of Songs 1:3 & 6:8.  It doesn't work.  It would be promoting the immorality of rock stars.  The Stone Tanach Orthodox Jewish translation (1998) says that the almoth means "maidens" in the Song of Songs verses.  "Maiden" means a woman who had not married. The almoth in Song of Songs 6:8 are not married to the king because then they would be included in the "queens" and "concubines".

I have listed all the occurances of almah in the Old Testament.  We know that the 1st instance, Rebekah in Gen 24:43 was a virgin, and we understand that the 2nd instance, Miriam was in Exo 2:8. "Virgin" works for all the other occurances.

Prov 30:19 
Singer and others claim that the almah in Prov 30:19 refers to the adulterous woman in v20 in the act of fornication. This is horrible. The adulterous woman in v20 is in contrast to the almah in v19, as is the case very often in Proverbs. The adulterous woman has no feeling, or rather pretends to have none, in complete contrast with the tender feeling of mighty man courting a virgin. The words in v18 "I know not" correspond to the word almah whose root means "unknown". "Wonderful" means "beyond human understanding", "marvelous". Adultery is not wonderful but the courting of a virgin by a mighty man is.
A commonly used Jewish exposition of Prov 30:18-20 is to ask, What is in common with these 4 wonders? The exposition says that the wonderful thing about all 4 is that they do not leave a trace. This is nonsense. There is no need to say that all 4 things must be wonderful in the same way; not leaving a trace is not wonderful; and adultery leaves traces. The common thing is that they are all wonderful, and probably are symbolic also.
(I think the 4 wonders are symbolic of the 4 stages of the Messiah: The eagle in the air is symbolic of Christ before incarnation (Mic 5:2; etc). The serpent on the rock is Christ incarnated in the form of sinful man, but without sin (Jn 3:14-15; etc). The way of a ship in the sea, is the resurrected Christ as a refuge to the church in the world (Heb 6:18-20; etc). The way of a mighty man with a virgin is Christ's marriage to the church at His 2nd coming and thereafter (Eph 5:22-33; etc). The unrepentant adulterous woman in v20 is the apostate church (Rev 2:20-25;etc) judged at Christ's 2nd coming. This is not necessary to the argument about almah here.)

Another terrible argument notes that the end of v19 literally says "the way of a mighty man in an almah" and expounds that the prepostion "in" refers to the physical intimate union of the man with the almah.  This gross misunderstanding may be because English translations translate the common Hebrew euphemism as "go in unto", but in Hebrew it just says "go to". The preposition used is el, "to" without the preposition "in" (Gen 6:4; etc).  The preposition "in" is used often for the relationship between a man and woman, but rarely, if ever, for the physical relationship (Deu 28:54; etc). Verses where "in" might be used for the physical are Gen 2:24 & 34:3, but these do not refer to the physical relationship but the cleaving together of the souls as stated in Gen 34:3 . Even if it does refer to the physical relationship in Gen 2:24, it is only with the verb "cleave" and would hardly infer that Prov 30:19 does.

Words close in meaning 
male form - alam
There are 3 Hebrew words which could mean "virgin". Almah, which is used here,  means an innocent young unmarried woman, from its usage throughout the Tanach and from its root meaning "unknown". The male form, alam, is an unknown or innocent young unmarried man.  The word is only used twice. It's 1st usage is 1 Sam 17:56, where the emphasis on David being unknown. The other usage is 1 Sam 20:22, where the point is that the alam  is innocent as to what is taking place.  

naarah - young unmarried woman 
Naarah is a young unmarried woman, but not necessarily, a virgin. The male form, naar, is a male youth, in age anywhere from an infant to just before marriage, equivalent to the English, "boy". It is used of Dinah after she had been raped (Gen 34:12) and of the widow Ruth (Ruth 2:5-6). It is not used of a married woman except in the case of a concubine who had left her husband (Jud 19:3-4) and of a woman who was just married, whose husband was trying to annul the marriage (Deu 22:15-16). If naarah were used in Isa 7:14, it would imply immorality.

Betulah, for which there is no masculine counterpart, is a woman virtuous in her relationship to men, whether an unmarried virgin or a wife of 1 husband from her virginity, not necessarily young. Joel 1:8; Es 2:17,19; Deu 22:19 are instances where betulah refers to married women. In Joel 1:8, the betulah has "the husband of her youth", which is similar to the phrase "wife of his youth" in Mal 2:15.  They have been married since their youth. Also the Hebrew word for "husband" here is baal, which never means "betrothed", but husband, as in Deut 21:13, where the betrothed does not become a husband until after the marriage is consumated.  

Whenever betulah is used to definately mean a virgin, additional words are added to make it clear that the the betulah is unmarried (Gen 24:16; etc). In Gen 24:16, it says that Rebekah was a betulah and no man had known her. The "and" means that "no man had known her" is something additional to her being a betulah.  The KJV term "damsel that is a virgin" in Deu 22:23,28 is the same in Hebrew as that translated "young virgin(s)" in Jd 21:12; 1 Ki 1:2 & Est 2:2-3. The Hebrew actually says naarah betulah. The meaning "young virgin" does not work in Deu 22:23 & 28 because the penalty should be the same whether the virgin was young or not, and if the meaning was "young", "young" would need to be defined. The meaning of naarah betulah is "unmarried betulah". This is almost the same as our English word "virgin", but could include a widowed betulah. If naarah betulah had been used in Isa 7:14, then the meaning could be that the father died before the child was born. If just betulah were used in Isa 7:14, it would be a normal birth.

The related word betulim, which is the masculine plural of betulah, means virginity (Lev 21:13;. Deu 22:14-15,17,20). This does not require that betulah means a virgin, but that the meaning is related to it.

The Sign: Butter and honey people shall eat v15-16 
v15 - This is the sign to Ahaz.

Literally, "Butter and honey he shall eat that he may know ..". "He" will eat butter and honey for the purpose that "he" may know to refuse the evil and choose the good. Why would eating butter and honey enable the child to refuse evil and choose good? I believe the answer is that "he" does not refer back to Immanuel, but to "people" (or "they") in "people shall call" in v14 according to DSS and Matthew 1:23. The "he" in v15, and the "people" in v14 are both 3ms, because in Hebrew that is used as the indefinite pronoun.

V15 should be translated, continuing the subject of the last phrase of v14 according to DSS: Butter & honey the people shall eat that they may know to refuse the evil and choose the good. "People" is the indefinite pronoun ("he" in Hebrew), and refers to the people of Judah in general as proven by 7:21-22. They would be purified by this simple diet as the new generation of Israelites was by the diet of manna in the wilderness. The reason the word "butter" or "curds" is used instead of milk is that milk and honey do not mix well. But honey mixes wonderfully with yogurt or butter. This is something the people will really eat. It is not just figurative. Hezekiah may have been prepared by this simple diet. Hezekiah may have learned to be simple to refuse evil and choose good through this time of discipline, during which he was just the right age to learn. In Isa 5:20, the Lord rebuked the people for saying the sweet was bitter and the bitter sweet. The simplicity promised in this verse is in contrast to Ahazís hypocricy (v12-13). Also see 8:6, where the people in general refuse (same word as in this verse) the waters of Shiloah and rejoice in Rezin and Remaliahís son.

The verse has a double meaning. One is the literal sign to Ahaz. The pronoun "he" or "they" also refers back to those who will call His name Immanuel. They will be nourished with the milk and honey of the word until they are mature for solid food. They will be purified from the puffing up of knowledge, from the tree of knowledge of good an evil, to the nourishment & enjoyment of the Lord as the pure milk of the word and honey. (1 Cor 3:2;Heb 5:12-13;1 Pet 2:2;Exo 3:8;16:31;Ps 19:10; 119:103; Prov 16:24;24:13-14;27:7;SS 2:3;5:16; Isa 5:20)

v16  - The meaning of the phrase "know to refuse the evil and choose the good" means something different in this verse than in the previous. In this verse, it refers to a little child reaching an age where he knows to refuse the evil and choose the good, which has nothing to do with eating butter and honey. It is common and normal, and happens with all normal boys when they reach age 2-3. In v15, "to know to refuse the evil and choose the good" refers to restoring the spiritual taste to the people in general.

I believe that the boy here, hanaar, is Mahershalahashbaz (8:1-4) who is called hanaar, "the boy," in 8:4. Many say the boy here is ShearJashub, Isaiahís son who was with him (7:3). I cannot find a parallel where a definite articled noun would refer back to someone mentioned 12 verses ago rather than the son mentioned 2 verses ago. (I only looked up all occurances of hanaar.) If it was refering to Shearjashub, who was there, I think it should say "this boy" rather than just "the boy". Also, we don't know how old Shearjashub is, but the boy here must be a newborn. Referring forward to 8:1 (9 verses) is also unusual. but this is a prophecy, so it can refer to someone coming. "The virgin" does not refer to anyone who was there, but to a particular virgin who was to come, but who had been mentioned before as "the woman" in Gen 3:15.

Reasons why hanaar refers to Mahershalalhashbaz rather than Shearjashub:
1. Since Shearjashub was there, referring to him would be better with the demonstrative pronoun, "this" then the definate article "the".
2. Mahershalalhasbaz is called hanaar in 8:4
3. 8:4 is the explanation of this verse, just as 7:21-22 is an explanation of 7:15.
4. The boy must be just born for the timing to work. If it was Shearjashub, then then we should be told how old Shearjashub is. If Shearjashub was just born, then Isaiah's wife could not have another child so soon.  

In the 3rd year of Ahaz, Pekah, son of Remaliah was killed and there followed 9 years of anarchy in Israel with no king. (2 Kg 15:30). Before this the king of Assyria took Damascus & slew Rezin (2 Kg 16:9).

The verse starts with "For". This verse gives the enabler for v14. If the confederacy of Syria with Ephraim were allowed to succeed, then the prophecies of the Messiah to be born could not be fulfilled.

Calvin and Benjamin Newton say "before the lad shall know to refuse the evil and choose the good" means that before anyone who at that time is a lad shall know to refuse the evil etc, the 2 kings would be gone. This interpretation is definately wrong. The Hebrew word, naar, usually means a young man, but can have the general meaning of "boy" which can refer to a boy from the age of infant to before marriage. A naar would generally already be of age to refuse the evil and choose the good. So this cannot refer to a "naar" in general.