You can claim anything... Islamist's claim They are first Hindus claim they are oldest. Now you seem to claim Zorostrianism is the oldest. I dont want to talk on this since i do not have a timemachine.. And i too do not have anything to prove that this g_d is true and that is false.
But
Regarding Isaiah there were Prophets before him...Infact Abraham is the Originator of Monoethism...who existed before Isiah before David before Moses.False g_ds existed before Abraham ..... Jews were exiled many times they had many enemies.. Are you saying that they acquired monoethism During the time of of Achaemenian Imperial Government's ... You can also say they might have acquired this idea from Egypt... You can go on...
