This is often a point of contention among many people, whether they be Jew, Christian, Muslim or who else. It has long been believed by the church that this mysterious entity is Jesus Christ in his prehuman existence. Justin Martyr himself not only identifies Christ as such in his Dialogue with Trypho the Jew, he identifies Jesus as the LORD of hosts.
Most Jews would object to the idea of God taking on human flesh with verses like Numbers 23:19, Hosea 11:9 and other passages, same with cult groups and Muslims. Although none of these passages actually deal with what Trinitarians believe. Yes, God is not a man, but that doesn't mean he cannot take on human flesh and not cease being God (to point of fact the context of those verse deal with God's trustworthiness that he will not lie). Biblical Christianity believes, that God the Son came down and took on flesh, but did not cease being God in heaven. The Father is not the Son, The Son is not the Spirit and the Spirit is not the Father.
I had a conversation with Funkdude regarding the Trinity and of course went to some relevant texts like Genesis 18 and Genesis 22. I said to him about Genesis 22 being argued 2 ways, that the angel is God or he is the representative. But I forgot that I am a Trinitarian, not a Unitarian. After contemplating on Genesis 22, I remembered that the members of the Godhead, specifically the Son and the Spirit can speak on behalf of the Father in heaven.
In other words, Genesis 22 still confirms to my realisation that it doesn't refute my position on the Angel of the LORD as God.
First of all, Jesus is not the Father, he is distinct from the Father, that is first an foremost.
Furthermore, it is important to remember that even though the Angel of the LORD speaks on behalf of the LORD, that is not what makes him God, it's when someone identifies himself as such.
It has been argued that Jacob wrestled with a mere angel based on the word Elohim. Why do I say that? The word Elohim can be used of mighty men, angels, judges, kings and false gods and doesn't always refer to the true God. This is true, but don't forget context determines the meaning. The problem with the assertion with the subject of Jacob and the angels fight is Jacob's own words, he says he saw God and lived, He didn't see God's glory obviously, but someone wants to argue that Jacob did not see God, they would have to prove that.
The LORD appears to Abraham in Genesis 18 and three men come to him, one of the men is idenified as God as indicated in the context. The man leave but HaShem is still present and Abraham stands before him, After their conversation, HaShem leaves but beforehand he says:
"Genesis 18:20 Then the Lord said, “The outcry against Sodom and Gomorrah is so great and their sin so grievous 21 that I will go down and see if what they have done is as bad as the outcry that has reached me. If not, I will know.”".
Yet when the men leave, HaShem hasn't left yet, and only goes once he has finished the conversation with Abraham.
Another context to consider is Judges 13 where the angel of the LORD tells Manoah about the son his wife will bare, and in the context he tells Manoah to present an offering to the LORD. Once the Angel departs, Monoah is shocked when he discovers he has spoken to the angel of the LORD and said “We are doomed to die! We have seen God!”".
Are you telling me, that the angel is a mere representative and is not God? I did say earlier that context determines if the angel is God or not and that speaking on behalf of God, is not what makes the angel God, that is important. We need to be careful when we look at the nature of the angel of the LORD. It is important to remember that Angel doesn't mean necessarily a created divine entity, Angel comes from angelos which means messenger and the Hebrew for messenger is malak.
There are Christians who suggest that all three members of the Trinity are seen in Genesis 18, but this an unwarranted interpretation and is not faithful to the text.
Not only this, but when you read Ezekiel 11:5, it says the Spirit of the LORD came to Ezekiel and said "This is what the LORD says". This is one of the few places in the TANAKH where the Holy Spirit himself actually speaks and is less ambigious than Isaiah 63:10 although the context can suggest the Holy Spirit of God being a distinct person from the Father, especially since Paul warns NOT to grieve the Holy Spirit and to point of fact the Holy Spirit functions as a divine person in the NT.
Again, It is not speaking on behalf of God that proves the Spirit being God, it's the context, just like with the Angel of the LORD.
With this in mind, shall we continue?