The early Church Fathers, as any new religious movement, would need to secure and protect their legitimacy as a religion. “Borrowing” key iconography from Judaism, they would need to fully secure their legitimacy vis à vis Judaism in particular. As the legitimacy of Judaism, direct heirs of Sinai, is somewhat difficult to undermine, and as the Church Fathers did not want to undermine ‘Sinai’ and/or the (Jewish) Bible, per se, the Church would employ a different tack.
The gambit that the Christians would take would be to steadily but surely undermine the character–reputation of the Jews. The Jews may have been distracted by the Roman invasion and expulsion from focusing much on the Christians. But the Christians were certainly focusing and polemicizing about the Jews. Step by step over the decades, and then over the centuries, this character assassination would proceed: first obliquely, then directly, and then directly and venomously.
The stage is first set in the gospels themselves. The Christian Fathers in the first several centuries then ratchet–up the intensity. Once hatred is sown, it tends to have a life of its own, or in the case of the Jews, probably more accurate to say – a death warrant all its own.
As the power of the Church increased by a quantum jump—with the de facto conversion of Constantine in the 300s CE—the Church did not back off from the concerted denigrations; but, rather, increased the intensity of the defamations and de–humanizations. Not only would the Jews be off–balance, and not in a position to politically or intellectually challenge the legitimacy of the Church, the Jews would be lucky to be left breathing.
*
Historically, Roman soldiers arranged the crucifixion start to finish of this brutal Roman execution mode.
There were no tribunals before the execution. No tribunals were needed, any which way, as Pontius Pilate had absolute power over these ‘local matters.’
The Jews under Rome were powerless to affect the outcome either which way.
The Romans feared sedition. The Romans executed many protagonists who threatened upheaval or worse. The Romans were messiah–averse. The Romans crucified lesser threats than Jesus.
Any hypothetical (Jewish) co–operation or collusion, even tangential, with Rome on this sordid matter would have been not only against Jewish law, but also contrary to the Jewish modus operandi spanning many centuries. Jesus may have been a threat to Rome, but Jesus does not appear in one single Jewish rabbinic text contemporaneous with that period.
So, how did the Jews become labeled by the Church as “Christ killers”?
With Rome ascendant, and the Church Fathers eager to recruit the inhabitants of the Roman Empire, increasingly the historical record is re–spun by the ascendant Church to diminish the role of Roman Procurator Pontius Pilate, and to increase, somehow, the alleged participation and capability of the Jews.
It would seem to be a challenging task to turn WHITE into BLACK, but that is the basic scenario.