If I were forced to come up with a theory along these lines I guess it would be something like this:
The "Jesus Christ" Paul was preaching was a figure like Enoch, derived from Jewish scriptures about Joshua son of Nun -- Joshua the Messiah. The Joshua of Paul was created through the process of pesher, whereby bits of scripture are taken out of context and reinterpreted, a common practice witnessed in the texts from Qurmran.
The Joshua Messiah of Paul had taken the form of flesh, lived in the distant past, had been hung on a tree, and had risen recently -- "the first fruits" of the resurrection.
Identifying Paul's Joshua from his pesher:
Galatians 3:
10 For all who rely on the works of the law are under a curse; for it is written, “Cursed is everyone who does not observe and obey all the things written in the book of the law.” 11 Now it is evident that no one is justified before God by the law; for “The one who is righteous will live by faith.” 12 But the law does not rest on faith; on the contrary, “Whoever does the works of the law will live by them.” 13 Christ redeemed us from the curse of the law by becoming a curse for us—for it is written, “Cursed is everyone who hangs on a tree”— 14 in order that in Christ Jesus the blessing of Abraham might come to the Gentiles, so that we might receive the promise of the Spirit through faith.
The Promise to Abraham
15 Brothers and sisters, I give an example from daily life: once a person’s will has been ratified, no one adds to it or annuls it. 16 Now the promises were made to Abraham and to his offspring; it does not say, “And to seeds,” as of many; but it says, “And to your seed,” that is, to one person, who is Christ. 17 My point is this: the law, which came four hundred thirty years later, does not annul a covenant previously ratified by God, so as to nullify the promise. 18 For if the inheritance comes from the law, it no longer comes from the promise; but God granted it to Abraham through the promise.
Galatians 4:
4 My point is this: heirs, as long as they are minors, are no better than slaves, though they are the owners of all the property; 2 but they remain under guardians and trustees until the date set by the father. 3 So with us; while we were minors, we were enslaved to the elemental spirits of the world. 4 But when the fullness of time had come, God sent his Son, born of a woman, born under the law, 5 in order to redeem those who were under the law, so that we might receive adoption as children. 6 And because you are children, God has sent the Spirit of his Son into your hearts, crying, “Abba! Father!” 7 So you are no longer a slave but a child, and if a child then also an heir, through God.
The "fullness of time" refers to "four hundred thirty years" after God made his promise to Abraham.
Romans 5:
12 Therefore, just as sin came into the world through one man, and death came through sin, and so death spread to all because all have sinned— 13 sin was indeed in the world before the law, but sin is not reckoned when there is no law. 14 Yet death exercised dominion from Adam to Moses, even over those whose sins were not like the transgression of Adam, who is a type of the one who was to come.
15 But the free gift is not like the trespass. For if the many died through the one man’s trespass, much more surely have the grace of God and the free gift in the grace of the one man, Joshua the Messiah, abounded for the many.
I suspect that there was some pesher by which "son of Nun" was taken to mean "son of God". Paul talks about hidden mysteries.
Romans 16:
25 Now to God[m] who is able to strengthen you according to my gospel and the proclamation of Jesus Christ, according to the revelation of the mystery that was kept secret for long ages 26 but is now disclosed, and through the prophetic writings is made known to all the Gentiles,
Perhaps part of the mystery was that "son of Nun" = "son of God".
Numbers 8:
8 from the tribe of Ephraim, Hoshea son of Nun;... And Moses changed the name of Hoshea son of Nun to Joshua.
This changing of his name to "YWHY's salvation" was the revelation that he was the son of God.
The crucifixion of Joshua:
Joshua 8:
29 And he hanged the king of Ai on a tree until evening; and at sunset Joshua commanded, and they took his body down from the tree, threw it down at the entrance of the gate of the city, and raised over it a great heap of stones, which stands there to this day.
From this possibly some pesher was created whereby the king of Ai and Joshua were transposed. Part of the mystery is that it was really Joshua who was crucified, not the king. This could explain the Gospel tradition whereby Jesus was substituted for the one who was to be crucified, Barabbas.
How then to explain the fact that the Joshua story continues on, he's clearly not dead, its not his body under the stones? Don't have a good explanation for that other than resorting to mystical pesherism.
I'm not saying I think this to be true, I'm saying right now, this is the best I could come up with to try and make some kind of case of out this. I'm not saying its a good case. It's not horrible, but its certainly lacking at this point. But quite honestly, there aren't many other opportunities in the scriptures to identify anyone being hung on a tree that could be the Christ Paul is talking about.
Perhaps this could bring a new view of:
Galatians 3:
3 You foolish Galatians! Who has bewitched you? It was before your eyes {I showed you} that Joshua the Messiah was portrayed {forewritten} as crucified! 2 The only thing I want to learn from you is this: Did you receive the Spirit by doing the works of the law or by believing what you heard? 3 Are you so foolish? Having started with the Spirit, are you now ending with the flesh?
