This is an interesting discussion, and I have a definite bias here, but I'd like to point out something that hasn't been mentioned. The following prophecy has received some attention in this thread:
Psalms 2:7 NKJV "I will declare the decree: The LORD has said to Me, 'You are My Son, Today I have begotten You.
However, the timing of the fulfillment is significant to this debate. Some say it applies to Jesus' birth, but the following passages give us another possibility:
Acts 13:33-35 NKJV God has fulfilled this for us their children, in that He has raised up Jesus. As it is also written in the second Psalm: 'YOU ARE MY SON, TODAY I HAVE BEGOTTEN YOU.' (34) And that He raised Him from the dead, no more to return to corruption, He has spoken thus: 'I WILL GIVE YOU THE SURE MERCIES OF DAVID.' (35) Therefore He also says in another Psalm: 'YOU WILL NOT ALLOW YOUR HOLY ONE TO SEE CORRUPTION.'
Hebrews 1:3-5 NKJV who being the brightness of His glory and the express image of His person, and upholding all things by the word of His power, when He had by Himself purged our sins, sat down at the right hand of the Majesty on high, (4) having become so much better than the angels, as He has by inheritance obtained a more excellent name than they. (5) For to which of the angels did He ever say: "YOU ARE MY SON, TODAY I HAVE BEGOTTEN YOU"? And again: "I WILL BE TO HIM A FATHER, AND HE SHALL BE TO ME A SON"?
Romans 1:3-4 NKJV concerning His Son Jesus Christ our Lord, who was born of the seed of David according to the flesh, (4) and declared to be the Son of God with power according to the Spirit of holiness, by the resurrection from the dead.
It seems to me that these verses indicate that the timing of the declaration calling Jesus the "Son" was made at the resurrection, not at His birth. This is significant in that it provides more evidence that Jesus preexisted His birth and was present at the creation in Genesis 1:26 and was spoken of as Creator in Col 1:16.
1 Corinthians 15:45 NKJV (45) And so it is written, "THE FIRST MAN ADAM BECAME A LIVING BEING." The last Adam became a life-giving spirit.
When did the "last Adam" become a life-giving spirit? It was when He was raised!
1 Peter 1:3 NKJV Blessed be the God and Father of our Lord Jesus Christ, who according to His abundant mercy has begotten us again to a living hope through the resurrection of Jesus Christ from the dead,
1 Peter 3:18, 21 NKJV For Christ also suffered once for sins, the just for the unjust, that He might bring us to God, being put to death in the flesh but made alive by the Spirit,
... (21) There is also an antitype which now saves us—baptism (not the removal of the filth of the flesh, but the answer of a good conscience toward God), through the resurrection of Jesus Christ,
We also are "begotten" children of God and grafted into His kingdom when we accept His Son's sacrifice, which is symbolized by baptism, not at our birth.
Also, the Father speaks to the Son saying, "O God." Notice this passage:
Hebrews 1:8-11 NKJV But to the Son He says: "YOUR THRONE, O GOD, IS FOREVER AND EVER; A SCEPTER OF RIGHTEOUSNESS IS THE SCEPTER OF YOUR KINGDOM. (9) YOU HAVE LOVED RIGHTEOUSNESS AND HATED LAWLESSNESS; THEREFORE GOD, YOUR GOD, HAS ANOINTED YOU WITH THE OIL OF GLADNESS MORE THAN YOUR COMPANIONS." (10) And: "YOU, LORD, IN THE BEGINNING LAID THE FOUNDATION OF THE EARTH, AND THE HEAVENS ARE THE WORK OF YOUR HANDS. (11) THEY WILL PERISH, BUT YOU REMAIN; AND THEY WILL ALL GROW OLD LIKE A GARMENT;
Further, who is the Son of Man?
Notice the plural "thrones" in this passage:
Daniel 7:9 NKJV "I watched till thrones were put in place, And the Ancient of Days was seated; His garment was white as snow, And the hair of His head was like pure wool. His throne was a fiery flame, Its wheels a burning fire;
Then we see His dramatic entrance:
Daniel 7:13-14 NKJV "I was watching in the night visions, And behold, One like the Son of Man, Coming with the clouds of heaven! He came to the Ancient of Days, And they brought Him near before Him. (14) Then to Him was given dominion and glory and a kingdom, That all peoples, nations, and languages should serve Him. His dominion is an everlasting dominion, Which shall not pass away, And His kingdom the one Which shall not be destroyed.
Consider also that God does not share His glory:
Isaiah 42:8 NKJV I am the LORD, that is My name; And My glory I will not give to another, Nor My praise to carved images.
Isaiah 48:11 NKJV For My own sake, for My own sake, I will do it; For how should My name be profaned? And I will not give My glory to another.
So when Jesus prayed, in John 17:5 NKJV saying, "And now, O Father, glorify Me together with Yourself, with the glory which I had with You before the world was," it was more than metaphor.
And the Pharisees heard Him clearly, when He said,
John 10:30-33 NKJV I and My Father are one." (31) Then the Jews took up stones again to stone Him. (32) Jesus answered them, "Many good works I have shown you from My Father. For which of those works do you stone Me?" (33) The Jews answered Him, saying, "For a good work we do not stone You, but for blasphemy, and because You, being a Man, make Yourself God."
This oneness echoes the "echad" unity spoken of since ancient times through the prophets.
Also,
John 5:17-18 NKJV But Jesus answered them, "My Father has been working until now, and I have been working." (18) Therefore the Jews sought all the more to kill Him, because He not only broke the Sabbath, but also said that God was His Father, making Himself equal with God.
Again,
John 8:57-59 NKJV Then the Jews said to Him, "You are not yet fifty years old, and have You seen Abraham?" (58) Jesus said to them, "Most assuredly, I say to you, before Abraham was, I AM." (59) Then they took up stones to throw at Him; but Jesus hid Himself and went out of the temple, going through the midst of them, and so passed by.
This reminded the Jews immediately of:
Exodus 3:14-15 NKJV And God said to Moses, "I AM WHO I AM." And He said, "Thus you shall say to the children of Israel, 'I AM has sent me to you.' " (15) Moreover God said to Moses, "Thus you shall say to the children of Israel: 'The LORD God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has sent me to you. This is My name forever, and this is My memorial to all generations.'
He claims the Name again three times (notice that the "He" is italicized, meaning it's not present in the Greek):
John 18:4-8 NKJV Jesus therefore, knowing all things that would come upon Him, went forward and said to them, "Whom are you seeking?" (5) They answered Him, "Jesus of Nazareth." Jesus said to them, "I am He." And Judas, who betrayed Him, also stood with them. (6) Now when He said to them, "I am He," they drew back and fell to the ground. (7) Then He asked them again, "Whom are you seeking?" And they said, "Jesus of Nazareth." (8) Jesus answered, "I have told you that I am He. Therefore, if you seek Me, let these go their way,"
Paul later speaks of the Son in this way:
Philippians 2:6 NKJV who, being in the form of God, did not consider it robbery to be equal with God,
and Colossians 2:9 NKJV For in Him dwells all the fullness of the Godhead bodily;
Anyway, I've probably thoroughly revealed my bias! For continued discussion, I wanted to add the timing of the fulfillment of the "You are My Son" prophecy for your prayerful consideration.