While this belief did enable man to reconcile the variables of chance with a concept of unchanging supermortal forces, this doctrine has ever since made it difficult for religionists to conceive of cosmic unity.  The concept of dual spiritism, good and bad spirits, gave rise to the later beliefs in white and black magic. 
The dual-spiritism concept of good and bad forces offered man ample opportunity to attempt to pit one agency against another, for, if a powerful man could vanquish a weaker one, then certainly a strong spirit could dominate an inferior ghost.  And this belief later became involved in the superstition of good and bad ghosts, good and bad spirits. 
Young Jesus was long willing to accept the doctrine of good spirits and evil spirits as the possible explanation of mental and spiritual phenomena, but he very early became doubtful that such unseen influences were responsible for the physical happenings of the natural world. 
Zoroaster was much affected by the prevalent concept of dual spiritism, the good and the bad, at the same time definitely exalted the idea of one eternal Deity and of the ultimate victory of light over darkness.