So far as I understand it, the general academic consensus is that Zoroastrianism originated monostheism before both Judaism and Akhenaten's reforms.
This has been my understanding as well. Even among non-academics. As I've mentioned before students affiliated with Catholic Church or schools appear to have been more cognizant of Zoroastrianism and one member even mentioned that Zoroaster was the first monotheist.
Of course, it does depend on how strictly we're defining monotheism.
I stand with Martin Haug that Zoroastrianism was indeed monotheism, their God and creator of the universe, Ahura Mazda, was omnipotent and responsible for having created his malfeastic adversary Angra Mainyu, And Spenta Mainyu is conceptually equivalent to the Holy Spirit in Christianity. So if one were to exclude Zoroastrianism from the gamut of monotheistic religions then one would have to exclude Judaism (because 1. strict monotheist statements do not appear in the Hebrew Bible until the Jews came into contact with the Zoroastrians and 2. afterwards there is mention of angels or spirits) Christianity, and Islam (because the Koran mentions angels or spirits as well). Also, in the end, the monotheistic traits of these "Levant" religions are resemblant enough that often times their members claim the God of these religions are essentially the same God.
I have told you that the peak of human consciousness is a state of oneness, at the same time, coming to this state was restricted to mystery schools for most of history - there are still many alive today, Freemasonry comes to mind, which teaches the transcendence of duality through ritualization which was common in all civilizations we have recorded. Truly, there is no religion which does not teach what you generalize as monotheism, and looking for the oldest isn't going to be particularly beneficial. Whatsoever helps you to attain this state should be the pursuit, not who did it first - whosoever it was is long dead, you are alive today.
I appreciate embracive culture, but in this case I do believe that it is important to understand who came up with the idea of monotheism first. For one thing religion and cultural heritage is tied to a communities identity and is about authority structures in a world where a cultural battle is being waged between "biopirates" and "fakelorists" and the real thing. There is a certain kind of truth to the fact that the ancient Aryans first conceived of God and not the Jews, the Christians, or the Muslims.
Well, gooolly, the Parsis and Iranian Zoroastrians are (obviously very closely connected) as are the Brahmins and Iranians. In Gujarat there is a very noticeable cross-blending between Parsi and non-Parsi. Indian and Pakistani Muslims are pretty much genetically the same as Hindus. Finally Yezidis (a sub-group of Yazadans) are more closely related to Iranians than Kurds.
So looks like there is a Zorastrian-Vedic-Yazadi ethnic relationship.
The difference between the Zartushtis of Iran and those of Gujarat is that the former have maintained the Aryan language whereas the latter gave up the Aryan language apart from the Avestan language which they use for liturgical purposes. But the Zartushtis or Iran, the Parsis, the Yezidi Kurds and the non-Yezidi Kurds all play an important part in the preservation of the Aryan cultural heritage.
Speaking of Mithraism and the Zoroastrian-Vedic-Yazadi you may want to look into the religion mentioned in this article:
"Abstract: According to the present article the first Iranian prophet who laid the foundation for sun worship (Mitraism) was called Mehabad. Abad Bozorg (the big Abad), who was a pious ruler in Iranovich was born 3593 years before the birth of Prophet Zoroaster. He laid the foundation of monotheism or divine worship and a constitution based on justice which was known as Mitradad." -
Zarathushtra; The First Monotheist Prophet (CAIS)
The following article has some citations relating to the topic... I was already familiar with some of Wallis Budge statements about ancient monotheism in Egypt:
The Concept of Monotheism Since Ancient Times
Vedic monotheism:
http://www.asvattha.org/Data/Article021.pdf
Coomaraswamy - Vedic "Monotheism"
I've heard this before. That it was really monotheism, praise of the "father or sky god" that preceded polytheism. The interesting thing is that people oftentimes regard Zaratushtra as having been a reformer of religion in the sense that he brought about monotheism, but some authors on the subject have depicted quite a different picture implying that monotheism existed long before Zarthushtra, but began to devolve into polytheistic idol worship, and saw Zarathushtra as more of a restorer of the good religion than a reformer. As far back as the Irano-Aryans can recall they have been monotheists whereas the Hindus, Greeks, Italic, Celtic, Germanic, Armenian, Baltaic, Slavic, and Albanian mythology consists of polytheism before their conversion to Christianity or Islam.
