As my argument goes, the steps are the following:Giuseppe, unfortunately your position seems circular to me and lacking in a logical thread. I feel you wish to rush to conclusions without providing a step by step approach.
There is nothing wrong with you rejecting that Paul wrote about a historical Jesus, but to convince me you would need to engage with the evidence reference by reference and not dismiss them by saying “epistles of ''Paul'' are entirely silent on the HJ -- because never existed one”.
1) midrash from Josephus insignia episode proves that Pilate was introduced in the first Gospel deliberately to show the Jews as perfidious conspirators acting behind the scenes (and not the contrary: that Jews had to be at any cost ''bad'' to ingratiate so the Romans).
2) Because the introduction of Gospel Pilate implies by logical effect the Roman crucifixion of Jesus, then the point 1 proves that Jesus was not crucified by Romans (but it doesn't prove that Jesus didn't exist).
3) the Jews, under the Roman rule, cannot crucify no man (a point you give me free contra outhouse).
4) Therefore: points 2 and 3 prove that Jesus was not crucified by no man (Roman or Jew).
5) This is confirmed in the Jewish reaction described in the Talmud. Peter Shafer proves in his book that a recurring pattern in all Talmudic stories about Jesus is the attribution of direct responsibility for his death, with much of a legal process, always and only on the Jews themselves. If the Romans were the real killers of Jesus, why did the Talmudists insist that were instead them, the same Jews, the true killers of Jesus? The more economic explanation, in my view and given the points 1-4, is that they did so because they had understand pratically the point 1 (that the unique theological/propagandistic raison d'être of Pilate in the Gospel is to despise the perfidious Jews) -- even if they assumed in while the Gospel story as ''Remembered Christian History'' and not as pure fiction (i.e.: even if they were Gospel-based historicist).
6) I think the epistles of ''Paul'' were composed after the first Gospels. I am satisfied by Detering's proof of the fabrication of that letters in II CE. Even if it's not a conclusive proof. But Detering doesn't say that the epistles follow the Gospels (he may even accept the contrary, as does Bob Price). I think so because more or less the first Gospels (Mcn , Matthew, Mark) give a negative portrait of the disciples (even if Matthew tries to rehabilitate partially them against the Mcn's defamation), but not still a portrait of the True Disciple/Witness par excellence. I find that need as entirely satisfied by the invention of ''Paul''.
The epistles show a knowledge of the Gospel Jesus because Galatians assumes as background a Paul coming from Diaspora to show his Good News to Pillars of Jerusalem, therefore confirming a priori the assumption of a ideal Gospel Jerusalem post-Resurrection.
The original marcionite epistles don't show a knowledge of a HJ because they do not add anything of different to the Gospel Jesus (already an angelic being in Mcn) that is historical and/or realistic, saying only that he was crucified by ''the archons'' (i.e. demons acting behind the Jews, the latter in turn acting behind the Romans) ''of this eon'', who Jesus rose and revealed to Paul the true message of Jesus. These epistles quoted the Eucharist episode (already found in the Gospel) but don't add nothing about a Gospel itinerant Jesus because in a marcionite view that preaching was in vain (kata sarka), since neither the Jews nor even his Jewish disciples had understood and/or liked the true message of Jesus. This is the reason because a itinerant teacher Gospel Jesus didn't find mention in the original marcionite letters.
I have mentioned the Niehoff but his case about the Jewish source is not conclusive. I think you agree that this ''Jewish source'', if existed, repeats the same Talmudic defamations (about a Jesus son of a Roman soldier, usurper, magician, etc.) but it's difficult to say if it did deny also the Pilate responsability or not, because it's difficult to know when is the pagan Celsus the author of the Pilate reference, or his hypothetical Jewish source. What I see is that Pilate/Jesus relation is not found in the Talmud. Note that I don't claim that the Talmudists were not historicist. I claim they were historicist because (like Celsus) they were Gospel-based, but deniers of any role of killer for Pilate.When discussing the “Jewish text” behind Celsus I am not convinced you have provided any evidence against my suggestions. However now you wish to ignore this and discuss how Origen interpreted Celsus. As I said Niehoff says that Origen wrote after 250 CE.
All Celsus utility in my opinion is reduced only to his put ''with the backs to the wall'' Origen, forcing him to say what secular evidence he has about Jesus. The answer of Origen betrays that he had no secular evidence of Jesus, outside of the Gospel. The best economic explanation for this fact is that that secular evidence did not exist. This is definitely most expected if Jesus never existed than the reverse.I think it might be possible for you and me to agree with Origen – “there are no other sources to the life of Jesus accept those found in the Christian traditions including the gospels and the Pauline epistles.” However where we differ is how we considers these texts.
As I said above, it's difficult to know if that Jewish source did accept the Pilate episode or not, because Celsus did accept it and he could have overlapped his opinion with that of his Jewish source about the specific Pilate episode.I would like to slow down the debate and request that you start presenting your case about the Jews taking responsibility for the death of Jesus from the “Jewish text” behind Celsus, because I don’t think there is any.