I'm not entirely sure myself, I'm still trying to figure it out. One issue is that we really don't know anything about the earliest Christ worshipers other than what Paul tells us, and we don't know how representative his views were.
What I've been able to piece together is something along these lines:
1) It was believed that the Final Judgment was at hand. (I believe this was a result of the death of King Agrippa in 44.)
2) Joshua the Anointed was going to be the judge who executed the Final Judgement.
3) Having faith in Joshua was key to ensuring that Joshua judged you favorably.
That's sort of "step one". This version of Christ worship applied primarily to Jews.
Prior to Paul even, a Gentile expansion of this outlook took place. Believing that the Final Judgment was at hand, certain Jews wanted to save the Gentiles from the Final Judgement. They proselytized to God-fearers, telling them about the coming Judgement and telling them that they needed faith in Joshua in order to avoid judgement, and they also needed to enter the covenant of Abraham.
Here we get a split. There were Jews that asserted this required circumcision, and other Jews (prior to Paul) who asserted that they didn't need circumcision, only faith in Joshua the Anointed. This is where persecution came in -- persecution of those claiming to convert Gentiles without having them undergo circumcision. Paul began by persecuting these groups of non-circumcisers.
Then Paul came to the understanding that the Final Judgement was eminent, so Paul too adopted the circumcision-free model, in order to convert as many Gentiles as possible prior to the Final Judgement.
Now we pick up with Paul's logic.
God's promise of redemption only applied to Abraham and his descendant Joshua the Anointed, whom God named.
Paul's logic appears to be that at some point (when that is I'm trying to figure out) Joshua the Anointed was hung on a tree as a sacrifice to redeem all those who lived under the law, i.e. practiced circumcision. This is necessary because it is impossible to actually obey the law. Paul's logic about the law is that the law is impossible to follow, so everyone who is under the law is cursed, because inevitably, everyone breaks the law. So Joshua hung himself on a tree to take everyone's curses onto himself. At some later time (3 days, a year, thousands of years?) Joshua was raised from the dead in preparation for the Final Judgment. The raising of Joshua from the dead was the sign that the Judgement was at hand. Now that Joshua was raised from the dead, his Spirt went out to all the Gentiles.
Now all of the Gentiles could enter the covenant of Abraham purely through faith in God's promise of redemption, which was expressed by believing that God had in fact raised Joshua the Anointed from the dead. So if you believed that God had raised Joshua from the dead, that's all God asked of you, he no longer required that you show devotion to him through circumcision.
The question is, who is Joshua the Anointed? Is it Joshua son of Nun? It is a hidden figure whose identity is revealed through peshers using scriptures about Joshua son of Nun and Joshua son of Jehozadak, the stories of which are actually allegories that reveal the truth about a hidden mystical Joshua?
What's clear is this. The raising of Joshua from the dead was a sign that the Final Judgment was at hand. There must have been some preexisting concept about the raising of Joshua from the dead being a sign of the End Times. I believe that whatever Joshua Paul was talking about, its some Joshua who had ben dead for a long time. This wasn't a recently killed figure, this was a figure that had been dead for thousands of years.
Ezekiel 37, the prophecy of the dry bones, has something to do with the concepts about the raising of the dead and faith in the Lord.
4 Then he said to me, “Prophesy to these bones and say to them, ‘Dry bones, hear the word of the Lord! 5 This is what the Sovereign Lord says to these bones: I will make breath enter you, and you will come to life. 6 I will attach tendons to you and make flesh come upon you and cover you with skin; I will put breath in you, and you will come to life. Then you will know that I am the Lord.’”
7 So I prophesied as I was commanded. And as I was prophesying, there was a noise, a rattling sound, and the bones came together, bone to bone. 8 I looked, and tendons and flesh appeared on them and skin covered them, but there was no breath in them.
9 Then he said to me, “Prophesy to the breath; prophesy, son of man, and say to it, ‘This is what the Sovereign Lord says: Come, breath, from the four winds and breathe into these slain, that they may live.’” 10 So I prophesied as he commanded me, and breath entered them; they came to life and stood up on their feet—a vast army.
11 Then he said to me: “Son of man, these bones are the people of Israel. They say, ‘Our bones are dried up and our hope is gone; we are cut off.’ 12 Therefore prophesy and say to them: ‘This is what the Sovereign Lord says: My people, I am going to open your graves and bring you up from them; I will bring you back to the land of Israel. 13 Then you, my people, will know that I am the Lord, when I open your graves and bring you up from them. 14 I will put my Spirit in you and you will live, and I will settle you in your own land. Then you will know that I the Lord have spoken, and I have done it, declares the Lord.’”
As in this story, the dead who are raised are ancient Israelites. I think Joshua was also an ancient figure, a figure of dry bones, whose breath of life was put back into him by the Lord, showing that now was the time that had spoken and announced the Final Judgement.
