The Priesthood trying to harm Zarathustra.
Zarathustra's birth is described in a very old Iranian book: the DENKARD, Book 5, "The Life of Zarathushtra, and other marvels" (Translated by E. W. West, from Sacred Books of the East, volume 5, Oxford University Press, 1897). We read in CHAPTER 2.:
In the pure light and equal to the archangels -- collected together and reckoned together, since the original creation, and completely unmixed -- Zartosht (Zarathustra) was spiritually fashioned and provided undefectively for the acceptance and propagation of the religion in the world. 2. And when he is sent for the manifestation of restrained saintliness (mokih) and bodily substance, great glory and radiance become as much discernible in him as the same had come into the posterity of Yim [Jamshed] who are Pourushasp, his father, and Dukdaub who is his mother; and also while he is being born and for the duration of life, he produced a radiance, glow, and brilliance from the place of his own abode, that issued intensely and strongly, like the splendor of fire, to distant lands.
Also about the wizards and witches, tyrants, Kigs, and Karbs, and other miscreants who have produced outrage for him during his birth and childhood, with desire for his destruction; who have manifestly come about his death or disablement, and even so far as those who have come into the visible assembly about the destruction of his glory and other causes of helplessness. 4. And also including the wolves and other wild beasts, to whom he was cast forth by those of Pourushasp's kinsmen who were wizards, and the kindred of those frequenting demon-worship, but only as a test.
In like manner it is declared that, on account of Vohuman being welcome to him, he laughed outright at birth. 6. His coming for conference with Ohrmazd, and owing to his accepting the religion, Ahriman and many demons and fiends have come to him with exhibition of fear, offering of service, and the argument and entreaty of supplicants; and all these have returned from him disapprovingly, defeatedly, and confusedly, through the pure proclamation of his Avesta, the unique perfection of Ohrmazd's will, and the indication of a prepared armament (virasto-zenih), a declared reward, powerful sovereignty, and a way of injury to the destroyer.
Also the triumph of the sacred beings in the end, and the peculiarity of the joint control of the demons; how, before that, they rushed openly into the world and have dwindled, their bodily forms are shattered, and they are so converted into secret decay, that their supplicants, deceived and deceivers, became awful disputants through confession of it.
When the Priests found out that Zarathustra was going to be born, who would try to eliminate them and break their might, they set out trying to kill him, or at least harm him as much as possible even before he was born, by trying to harm his mother-to-be, while she was still expectant of him.
The Priests derive their might from winning over spiritual power to their side by pleasing whatever Spirits they may be able to communicate with. But as the Spiritual World lives entirely of "Soul Food" (that is: the emotions from the beings, living in the material world) the Priests will try to gather as many followers as they can to send their energy towards whatever spiritual being they communicate with. This is the same principle with any religion run by professional priests, who most often also have no other means to provide their daily bread. Many techniques have been used, from Mithraïstic times up till now, but in the essence they all work according to this very same principle. They all do need all kind of special buildings (to capture and isolate), clothing and rituals with related objects to fulfill the purpose.
But Zarathustra taught that there were other things than sacrificing to please the One God, and that whenever a sincere prayer is directly sent toward the One God (who always is in full possession of all those qualities that "false" gods or spirits may pretend to have, and even more) by any individual, this may be done so anywhere, at any time ! The Good Sraosha will always listen.
The only requisites in Zarathustrian prayer are, when praying the Ashem Vohu or the Yatha Ahu Vairyo (the two Prayers that already existed before Zarathustra, in fact already since creation) that, while praying, the Power of the Staota will only be effective if their holy language ("Gathic") is understood and also pronounced correctly and sincerely.
