For evolutionary reasons Asuras and Devatas fought great battles. Ādityas, sons of Rishi Kashyap and Aditi always followed the guidance of Trimurti, or the Trinity of Brahma, Vishnu and Shiva and are responsible for proper functioning of the universe, Asuras challenged their authority at various occasions. Most significantly there are constant battles for the Elixir of Immortality, called Amrit, between the two. This could explain why Avestan Asura-Mazda advised his followers to stay away from Daivas or Vedic Devatas, calling them untrustworthy and unscrupulous shining beings to be avoided at all cost.