Hi IWantAnguish and KingJimmy,
First, here is a link to an online Sacred Names Bible (KJV), which shows which name appears in the Hebrew (Old Testament), for God.
A famous landmark in scripture is Deu 6:4: Hear, O Israel: YHVH our ELOHIYM is one YHVH:
Another is Gen 1, where the same name - ELOHIYM - is used 32 times - and it's plural:
26 And ELOHIYM 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 ELOHIYM created man in his own image, in the image of ELOHIYM created he him; male and female created he them.
According to Newberry it occurs around 2,500 times, and is used with both singular and plural verbs, nouns and pronouns.
I don't think there is any way that a Hebrew could have grown up not knowing the name 'Elohiym', and not understanding that this plural name referred to 'one God'.
The Trinty as a doctrine after the New Testament era was brought in to combat heresy. But a Jew would not have been in doubt that God is both singular and plural according to His own definition of Himself. I believe Elohiym is not limited to three.
Do modern day Jewish-Christians view Jesus as the God of the Old Testament?
[url=http://www.afii.org/]http://www.afii.org/[/url] is a very useful website for gaining an insight to what modern day Jews understand from the Old Testament, with regard to Jesus.
(Christianity was preached from the Old Testament, so the promise of the Messiah there, had ALL to come together on one Man. This webpage is about that: [url=http://www.afii.org/texts/hw2p2rb.htm]Credentials of Messiah[/url])
Necessarily therefore, Jesus was the manifestation of the God of the Old Testament, and He unreservedly makes that claim for Himself many times over while establishing new parameters for man's relationship with God. But it was this - that Messiah [i]was God[/i], that Jews were unprepred for. They knew Messiah would be one of them and that was terribly important for establishing that He'was indeed Messiah. But, manifestly, Jews had a great deal of difficulty with the mysterious connections hidden in scripture, such that it's not until after Jesus' resurrection, that He begins to open a deeper understanding of it to His own disciples (to whom it was given to understand).
Jews imagined that Messiah being man, would give them some part in their own salvation. Rom 10:2, 3. When God took one side of Christ's descent into His own hands, no-one could really grasp what was going on - especially His changing His natural descent to be reckoned through a woman, rather than a man. Nevertheless, it is tremendously important to any Jew, that their Messiah did come, if they believe in Him. (We know that many did not.)
Your reference to John 6:46 does, I believe, leaves plenty of room for a spiritual interpretation, if the emphasis is put on the word 'seen'. Because - to take a purely human example - your father is seen in you, and my father is seen in me. Even if we didn't know who our fathers are, our existence proves we have a father. It's the same with Jesus, refering to God as His Father, in its intimate meaning (as compared with its religious, ritual significance). We 'see' the Father, in Christ, and Christ as the Firstborn (from the dead) sent by His Father as emissary, represents His Father (back home in glory), to those He meets in His journey to a distant country.
It is modern [i]gentile[/i] Christians, who have separated the Old and New Testaments unnecessarily, treating the Old Testament of little or no significance, mainly because of their own ignorance (imho). To a Jew though, that could not happen, except where his family have chosen to deny God's claims, or resist them.