Jesus is a member of the Godhead from before the foundation of the world. The Apostle John taught this in John 1:1-3 and 14.
John 1:1-3, 14
1 In the beginning was the Word, and the Word was with God, and the Word was God.
2 The same was in the beginning with God.
3 All things were made by him; and without him was not any thing made that was made.
14 And the Word was made flesh, and dwelt among us, (and we beheld his
glory, the glory as of the only begotten of the Father,) full of grace and truth.
In this verse we learn that the Word was God and that he created all things and that he was made flesh and dwelt among us and was the only begotten of the Father.
When we read Genesis we learn that there was more than one involved in the creation:
Genesis 1:26-27
26 And God said, Let
us make man in
our image, after
our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.
27 So God created man in his own image, in the image of God created he him; male and female created he them.
The use of the pronouns US and OUR tell us that God consists of more than one and that Jesus was there with the Father when they both decided to create the earth and that he was part of the God head.
We learn that Jesus was actually the God of the Old Testament named Jehovah and the Great I AM.
Exodus 6:2-3
2 And God spake unto Moses, and said unto him, I am the Lord:
3 And I appeared unto Abraham, unto Isaac, and unto Jacob, by the name of God Almighty, but by my name Jehovah was I not known to them.
Exodus 3:14-15
14 And God said unto Moses, I Am That I Am: and he said, Thus shalt thou say unto the children of Israel, I Am hath sent me unto you.
15 And God said moreover unto Moses, Thus shalt thou say unto the children of Israel, The Lord God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, hath sent me unto you: this is my name for ever, and this is my memorial unto all generations.
From these verses we learn that the God who appeared to Abraham, Isaac, Jacob, and Moses was Jehovah and was also known as I AM and God. It is important to understand that the Great IAM appeared to these ancient prophet and spoke to them face to face.
Genesis 32:30
30 And Jacob called the name of the place Peniel: for I have seen God face to face, and my life is preserved.
Exodus 33:11
11 And the Lord spake unto Moses face to face, as a man speaketh unto his friend. And he turned again into the camp: but his servant Joshua, the son of Nun, a young man, departed not out of the tabernacle.
Here we learn that God spoke to his prophets face to face as a man speaketh unto his friends. Was this God the Father or Jesus Christ? The Apostle John lets us know that this was not God the Father in the following verse:
John 1:18
18 No man hath seen God at any time; the only begotten Son, which is in the bosom of the Father, he hath declared him.
Here John, when speaking of God distinguishes his from the Son and tells us that no man hath see God, ie the Father. If no man had seen God the Father, then who was it that appeared to Abraham, Isaac, Jacob, and Moses? Was it not God the Son? Jehovah or the Great I AM? In the New Testament Jesus tells us that he is I AM.
John 8:52-59
52 Then said the Jews unto him, Now we know that thou hast a devil. Abraham is dead, and the prophets; and thou sayest, If a man keep my saying, he shall never taste of death.
53 Art thou greater than our father Abraham, which is dead? and the prophets are dead: whom makest thou thyself?
54 Jesus answered, If I honour myself, my honour is nothing: it is my
Father that honoureth me; of whom ye say, that he is your God:
55 Yet ye have not known him; but I know him: and if I should say, I know him not, I shall be a liar like unto you: but I know him, and keep his saying.
56 Your father Abraham rejoiced to see my day: and he saw it, and was glad.
57 Then said the Jews unto him, Thou art not yet fifty years old, and hast thou seen Abraham?
58 Jesus said unto them, Verily, verily, I say unto you,
Before Abraham was, I Am.
59 Then took they up stones to cast at him: but Jesus hid himself, and went out of the temple, going through the midst of them, and so passed by.
Here Jesus claimed to be the Great I AM. for this the Jews took up stones to cast at him.