Due to my ignorance and Western-centric education, I did not realize that Zoroastrianism is a monotheistic religion. Good revelation; a good kick in the butt for me.
It is debatable how monotheistic Zoroastrianism actually is. It seems that in order for the unification and reformist program vis-à-vis the preexisting polytheism(s) to develop, some polytheistic elements were tolerated more than others and some (demi)gods were demoted to a status more like that of angels or of so-called principles.
According to Encyclopedia Britannica:
«Though Zoroastrianism was never, even in the thinking of its founder, as insistently monotheistic as, for instance, Judaism or Islam, it does represent an original attempt at unifying under the worship of one supreme god a polytheistic religion comparable to those of the ancient Greeks, Latins, Indians, and other early peoples.»
See the full entry here: https://www.britannica.com/topic/Zoroastrianism
Joseph Tham I have never heard of any Zoroastrian groups being called "extremist" or "radical"; those adjectives are typically applied to Islamic persecutors of Zoroastrians. Where did you come across those designations?