Mazdaism is the proper name of Zoroastrism.
The faith in Ahura Mazda (Divine Mind/Wisdom), the Great God and only creator of the reality, has been proclamed by his prophet Zarathustra (Zoroaster) as the original faith of the Aryans (Indo-europeans and Indo-Iranians).
In the Gathas, the oldest poetic sacred text of Mazdaism, Zarathustra proclaims that Mazda(Mind/Wisdom) created all from its' pure light-energy/holy spirit (Spenta-Maniyu) and no-evil ever appeared from him.
Zarathustra further declared that all other "divinities" that claim to be omnipotent are liars, the Devas (ancient divinities of the Hinduist Aryans) are specificaly mentionned as liars and "counterfeit gods".
The believers in Mazda are asked to reject the worship of Devas because these "divinities" are not the true creators and are not the true gods of the Aryans.
Thus in the Mazdaism, Zarathustra claims to bring back Aryans to a monotheistic religions that he presents as their original faith.
Other divine beings also exist in Mazdaism, Mitra is one of them (he is also an early indo-european Hinduist god), but all these divine/heavenly beings are creatures of Ahura Mazda and are the equivalent of the angels of the Semitic Monotheist religions. The belief in angels was imported by the Jews from Babylone where they were in close contact with Zoroastrian Persians and the first Jewish sect that adhered to the belief in angels were called Pharisians, their name being a deformation of Farisi-Persian.
The name of these minor heavenly beings in Mazdaism is Asuras, which correlates with the name of the Hinduism Devas' ennemies the Asuras-demon warriors.
Thus the heavenly beings of Mazdaism are the demons of Hinduism, while the gods of Hinduism are the demons of Mazdaism.
In Mazdaism he Devas are the servitors of the Lie, the destructive spirit Angra Maniyu. Angra Maniyu is the absolute antithesis of Mazda's Spenta Maniyu. He is the equivalent of the Semitic Monotheist religions' Satan.
This could suggest a religious split between "Monotheists" and "Polytheists" in the early indo-european religious tradition.
The followers of Spenta Maniyu and Angra Maniyu are supposed to fight a final cosmic battle at the end of the times. The followers of Mazda's Spenta Maniyu are to be led by the Shaoshyant, the righteous leader (or leaders) of the forces of the Light.
The figure of the Shaoshyant can be recognized in the Jewish Mashiah, the Christian second comming of Jesus and the Muslim Mahdi.
The absolute opposition between Light/Good and Darkness/Evil in Mazdaism has led many to the wrong belief that Mazdaism is a dualistic religion.
But the only creator and the only origin of the reality in Mazdaism is Ahura Mazda, while Angra Maniyu can not create, but only pervert and destroy.
Thus Zarathustra has preached a Monotheist religion.
And of course the followers of Ahura Mazda have never worshiped fire, they simply used it as a symbol of the creative enrergy of Mazda, the holy spirit of Spenta Maniyu. http://en.citizendium.org/wiki/Zoroastrianism