Shortly after they pledged allegiance to the Yama Kings, the society of Daityas realized that the demons would only corrupt them and feed on their life energies and so they left the alliance. Through their own dark sorceries they, too, figured out how to maintain their bodies and avoid falling into nothingness as did the other Hsien.
The Daityas work to encourage the coming of the Sixth Age; to bring about a time when the August Personage of Jade is forced from his Celestial Court and the Dragons and Phoenixes war against each other in a bloody conflagration. By promoting lack of belief, they seek to weaken the wall created by the August Personage and so claim their rightful place in the Celestial Court.
Though misguided in the eyes of the other Hsien, they are not beyond redemption. If they wanted to do so, they could come back to the right path and help the Hsien in avoiding the Age of Sorrow.