See also: Ten Primordial Masters
Zarathustra (also known as Zoroaster) was a Persian prophet who founded a new religion.
Zarathustra (known to the Greeks as Zoroaster) preached that there is a supreme being, Ahura Mazda, who had created the world, mankind and all good things in it through his holy spirit, Spenta Mainyu. The rest of the universe was created by six other spirits, the Amesha Spentas ('holy immortals'). However, the order of this sevenfold creation was threatened by evil spirits, and it was therefore the duty of mankind to support the good spirits in order to speed up the destruction of evil. The main texts of Zoroastrianism are contained in the Avesta, the most sacred of which are the Gathas, or hymns of Zarathustra.
Shri Mataji Nirmala Devi has stated that Zarathustra was an incarnation of the Primordial Master. (1977-0321)
Zoroaster whom Parsees worship is nothing but an incarnation of Dattatreya, and you know how we worship him in our Sahaja Yoga, how we worship Mohamed Sahib in our Sahaja Yoga, how we understand where He stands within us. (1979-0929)
As I told you before that we had ten gurus who came on this earth and they represented the innocence of the three Brahma, Vishnu, Mahesha of Dattatreya and one of them was Zoroaster, another was Mohammed Sahib and all these gurus represent those qualities of innocence of these three personalities called as Dattatreya. (1984-0317)
This is Shri Datta Maharaj who is full of triguna (three attributes). He came in the world in form of Adiguru many times to teach how to cross the Bhavsagara (void). Yesterday I have told you that we fight in the world by forming many religions. The same Shri Datta incarnated many a times on the earth. As I told you yesterday, King Janaka was one of them. King Janaka was the father of Janaki (Sitaji). He was none other than the incarnation of Shri Dattatreya. Thereafter, Machindernath, most have you must have heard his name, was also His incarnation. After that Zoroaster, who came three times on the earth, he was also His incarnation. After that Mohammad Sahab, who was His incarnation. (1973-1209, translated from Hindi)