- Proves Jesus is the Messiah
- Proves the Bible is their god's word because it makes accurate prophesies
This neatly ignores the fact that the stories of Jesus' birth were written by people who knew the prophecies and wanted us to believe Jesus's birth was prophesied by the then well-known prophets. The prophet they quote is of course Isaiah.
Let's take a look at this prophecy.
And it came to pass in the days of Ahaz the son of Jotham, the son of Uzziah, king of Judah, that Rezin the king of Syria, and Pekah the son of Remaliah, king of Israel, went up toward Jerusalem to war against it, but could not prevail against it. And it was told the house of David, saying, Syria is confederate with Ephraim. And his heart was moved, and the heart of his people, as the trees of the wood are moved with the wind.
Then said the LORD unto Isaiah, Go forth now to meet Ahaz, thou, and Shearjashub thy son, at the end of the conduit of the upper pool in the highway of the fuller's field And say unto him, Take heed, and be quiet; fear not, neither be fainthearted for the two tails of these smoking firebrands, for the fierce anger of Rezin with Syria, and of the son of Remaliah. Because Syria, Ephraim, and the son of Remaliah, have taken evil counsel against thee, saying, Let us go up against Judah, and vex it, and let us make a breach therein for us, and set a king in the midst of it, even the son of Tabeal:
Thus saith the Lord GOD, It shall not stand, neither shall it come to pass. For the head of Syria is Damascus, and the head of Damascus is Rezin; and within threescore and five years shall Ephraim be broken, that it be not a people. And the head of Ephraim is Samaria, and the head of Samaria is Remaliah's son. If ye will not believe, surely ye shall not be established.
Moreover the LORD spake again unto Ahaz, saying, Ask thee a sign of the LORD thy God; ask it either in the depth, or in the height above. But Ahaz said, I will not ask, neither will I tempt the LORD. And he said, Hear ye now, O house of David; Is it a small thing for you to weary men, but will ye weary my God also?
Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel. Butter and honey shall he eat, that he may know to refuse the evil, and choose the good. For before the child shall know to refuse the evil, and choose the good, the land that thou abhorrest shall be forsaken of both her kings. The LORD shall bring upon thee, and upon thy people, and upon thy father's house, days that have not come, from the day that Ephraim departed from Judah; even the king of Assyria.
(Love the prickly pear cactus not introduced to the Middle East from the
Americas before the Sixteenth Century. Another prophecy?)
Firstly, this is quite probably a mistranslation. The original Hebrew text uses the term almah meaning 'young woman', that is, a girl who had not reached puberty. The Hebrew for virgin is bethulah. It has been argued that these two terms are synonyms but they are not. Almah would not be used to describe a sexually mature virgin and an almah may not necessarily have been a virgin. Almah clearly refers to the girl's physiological state and bethulah to her physical condition, or more precisely whether her hymen is intact or not.
So, when we see:
But while he thought on these things, behold, the angel of the LORD appeared unto him in a dream, saying, Joseph, thou son of David, fear not to take unto thee Mary thy wife: for that which is conceived in her is of the Holy Ghost. And she shall bring forth a son, and thou shalt call his name JESUS: for he shall save his people from their sins.
Now all this was done, that it might be fulfilled which was spoken of the Lord by the prophet, saying, Behold, a virgin shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us.
we can be sure that Matthew was using a Greek version of the Old Testament, the Septuagint, in which the Hebrew alma had been wrongly translated as παρθένα (parthenos). And this is a fairly good indication that he was trying to make sure his story had some scriptural basis and also that he was more familiar with Greek than with Hebrew.
Another problem with Matthew's use of this 'prophecy' is that nowhere else in the Bible is either the Messiah or Jesus ever referred to as Immanuel or Emmanuel.
But that is not the main problem with this prophecy.
The 'prophecy' very clearly, in the context of Chapters 7 and 8 of the Book of Isaiah is dealing with immediate events. Indeed in Chapter 8, almost casually, Isaiah refers to what seems to be his son by the prophetess whom he impregnated with his 'man pen', as O Immanuel. But the entire point of the prophecy seems to be that while this child is still young the enemies of Jerusalem will be defeated. And surely, for the supposed son of the Christian god, there would never be a time 'before [he] shall know to refuse the evil, and choose the good' (Isaiah 7:16) would there?
But even that is not the major objection to this being a prophecy about Jesus, whom, so it is claimed, was sent to Earth to provide mankind with henceforth the only way to salvation and eternal life in Heaven.
The main objection is: if God had already decided that a Messiah was what mankind needed, and that this was the way he was going to do it, why did he wait so long before providing that means? Biblical scholars date the 66 books of Isaiah as written by several authors between the eighth and sixth centuries BCE with the relevant Chapter 7 written in the eighth.
We are expect to believe that, having decided what mankind needed was a saviour Messiah to be sacrificed for our sins, and having told Isaiah to tell us about it, this 'omnibenevolent' god then waited another 800 years before providing it!
Pull the other one...