I have often wondered about the origins of Zoroastrianism. Its emergence seems to strangely coincide with the emergence of Judaism in the region, and all fact clearly supports the notion that the Jewish faith came first. While monotheism is not entirely unique in the world, it is still a rarity. I wonder if Zoroastrianism, with its teachings not all that dissimilar from those of the followers of Yahweh (or even later Christians) is, in fact, another (distant) branch of the Jewish faith.
To the contrary: the early Christians inherited their dualistic concept of good as against evil from the Zoroastrians. Judaism is remarkable free of any such Manichean concepts; while God may be the ultimate Good in a universal sense in Judaism, there is no evil corollary to him. Everything Christianity is is a plagiarization of a plagiarization.