Here the opposition between the good spirit of light and the demons of evilbetween Ormuzd and Ahrimans till remained the principal dogma of the creed; while all other gods and angels, however estimable their aid, were but subordinate servants of Ormuzd, whose highest manifestation on earth was not the sun-god Mithras, but the holy fire guarded by his priests.
In the Gathas the Good Spirit of Mazda and the Evil Spirit are the two great opposing forces in the world, and Ormazd himself is to a certain extent placed above them both.
By uttering a sacred formula the good spirit throws the evil one into a state of confusion for a second 3000 years, while he produces the archangels and the material creation, including the sun, moon and stars.
His guiding spirit is the Holy Spirit, which wills the good: yet it is not free, but restricted, in this temporal epoch, by its antagonist and own twin-brother (Yasna, 30, 3), the Evil Spirit (angro mainyush, Ahriman), who in the beginning was banished by the Good Spirit by means of the famous ban contained in Yasna, 45, 2, and since then drags out his existence in the darkness of Hell as the principle of ill - the arch-devil.
Describing the state of things in the beginning; the good spirit in endless light and omniscient, and the evil spirit in endless darkness and with limited knowledge.