Doug Mason: (QUOTE) "The "Judaism" of the "Old Testament" is not the Judaism of Jesus and his contemporaries. Much took place during the intervening centuries."
Well said Doug. The more we study, not just Judeo-christian religon, but ALL Eurasian religions, the more we will become aware of the cross-cultural influences evident in each religion.
The same goes for Zoroastrianism. There seems to be evidence that it too underwent modifications in its thought and beliefs. For those who wish to know a little more, Richard Folz's, 'Religions of the Silk Road,' (Second edition, 2010) has a reasonably brief summary of Zoroastrianism's development and its influence on the development of Judaism (See Ch 2, 'Religion and Trade in Ancient Eurasia.' )
Zoroaster, may have been a contemporary of Moses, both promoted something like monotheism (the Egyptian Pharaoh, Akhenaton may also have done the same and perhaps lived around the same era). The god that Zoroaster promoted was Ahura Mazda (See https://www.ancient.eu/Ahura_Mazda/ ).
Before Zoroaster lived, beliefs were prevalent in Iranian influenced areas? That's not completely clear, but likely beliefs werre similar, as essentially Zoroaster was a reformer. Iranian's generally had a common pantheon, perhaps with minor variations of belief, including myths and symbols. Likely 'fire temples' with a continually burning sacred flame (like many war memorials today) existed before (and after) Zoroaster's time. ( https://en.wikipedia.org/wiki/Fire_in_ancient_Iranian_culture )
Beliefs may also have varied after Zoroaster's time, as the religion was first codified from the the third century C.E. And, that's roughly the time that rabbinical Judaism and Christianity began a period of codification. The codification of Zoroastrianism began in the era when the Sasanian's had taken over the Empire from the Parthian's, which may indicate that religion was an issue in the competition between the Christian Roman Empire and the Sasanian (Iranian) Empire.
There's a lot more that we can know about this religion, and a lot we do not know. but I'll leave it there.