The pre-incarnate Christ is called "the Angel of the LORD" in the Old Testament, and He is recognized and worshipped as God. And it is He who appeared to Moses at the burning bush, where He was called "the LORD" (Yahweh) and also "God" (Elohim):
EXODUS 3: THE ANGEL OF THE LORD IS THE GOD OF ABRAHAM, ISAAC, AND JACOB
1 Now Moses kept the flock of Jethro his father in law, the priest of Midian: and he led the flock to the backside of the desert, and came to the mountain of God, even to Horeb.
2 And the angel of the LORD appeared unto him in a flame of fire out of the midst of a bush: and he looked, and, behold, the bush burned with fire, and the bush was not consumed.
3 And Moses said, I will now turn aside, and see this great sight, why the bush is not burnt.
4 And when the LORD saw that he turned aside to see, God called unto him out of the midst of the bush, and said, Moses, Moses. And he said, Here am I.
5 And he said, Draw not nigh hither: put off thy shoes from off thy feet, for the place whereon thou standest is holy ground.
6 Moreover he said, I am the God of thy father, the God of Abraham, the God of Isaac, and the God of Jacob. And Moses hid his face; for he was afraid to look upon God.
7 And the LORD said, I have surely seen the affliction of my people which are in Egypt, and have heard their cry by reason of their taskmasters; for I know their sorrows;
8And I am come down to deliver them out of the hand of the Egyptians, and to bring them up out of that land unto a good land and a large, unto a land flowing with milk and honey; unto the place of the Canaanites, and the Hittites, and the Amorites, and the Perizzites, and the Hivites, and the Jebusites.
9 Now therefore, behold, the cry of the children of Israel is come unto me: and I have also seen the oppression wherewith the Egyptians oppress them.
10 Come now therefore, and I will send thee unto Pharaoh, that thou mayest bring forth my people the children of Israel out of Egypt.
11 And Moses said unto God, Who am I, that I should go unto Pharaoh, and that I should bring forth the children of Israel out of Egypt?
12 And he said, Certainly I will be with thee; and this shall be a token unto thee, that I have sent thee: When thou hast brought forth the people out of Egypt, ye shall serve God upon this mountain.
13 And Moses said unto God, Behold, when I come unto the children of Israel, and shall say unto them, The God of your fathers hath sent me unto you; and they shall say to me, What is his name? what shall I say unto them?
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.
16 Go, and gather the elders of Israel together, and say unto them, The LORD God of your fathers, the God of Abraham, of Isaac, and of Jacob, appeared unto me, saying, I have surely visited you, and seen that which is done to you in Egypt:
As we can see, "this is my name for ever, and this is my memorial unto all generations" is a reference to "I AM THAT I AM" or "I AM" [the personal name of Jehovah (Yahweh)]. This speaks of the self-existence of God from eternity.
Now when we turn to the New Testament, Jesus of Nazareth calls Himself "I AM" and tells the unbelieving Jews that if they do not believe that He is "I AM" they will die in their sins.
JOHN 8: JESUS DECLARES THAT HE IS "I AM"
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. [Note: the KJV tranlators failed to capitalize "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.
What do we note here? (1) Jesus said that He has existed BEFORE Abraham. How could that be unless He is God. When He said "verily, verily" He meant "without the shadow of a doubt". (2) Jesus said that He is "I AM". The Jews knew from their reading of the Torah that "I AM" is the name of Almighty God. But they refused to believe Jesus. Therefore they took up stones to stone Him for blasphemy.
Before this, here is what Jesus said about Himself in verse 24: I said therefore unto you, that ye shall die in your sins: for if ye believe not that I AM [he], ye shall die in your sins.
Please note that "he" is in italics because the translators mistakenly inserted it there. They also failed to capitalize "I AM". Had they done so, the meaning of that statement would have been very clear. "If you do not believe that I AM (God), your will die in your sins".
