By experiencing the effects of its actions the evolving soul learns to discriminate between "good" and "evil" in the sense of those actions pursuing, and those actions opposing the path of Highest Wisdom; those actions promoting self and ego versus those actions reflecting the greatest universal good; those actions which are creative, and those actions which are anti-creative, or destructive.
The soul thus gains a greater depth of wisdom than would otherwise be obtained by following the "straight and narrow path". It is only through a knowledge of "evil", both its causes and its effects, that the evolving soul can comprehend "good" in the full and genuine knowing which comes of physical and emotional experience. For learning does not come without suffering; indeed experiencing the ill-effects of inappropriate actions is the essential key to learning, and thus an important element of evolution.
The concentration by the ego on self-motivation and self-interest which is the dominant feature of the lower end of the evolutionary journey leads inevitably to competitive mutual conflict, as each ego-individual tries to profit from and "get the better of" others. This explains why political and social relationships on Earth have tended to dominate human thought and group activity. It also explains why we have thus far failed so abysmally to live at peace with one another. The simple rule of correct political behavior, namely that we do nothing which is harmful to others, is accepted on almost all worlds except Earth.
This self-centered concentration on developing an individuality at the expense of others has led to most of the problems experienced by humanity throughout Earth's history. And it has caused many souls to "fall" even further. Through negative deeds and thoughts manifested in various forms of oppression, murder, torture and perversion, these souls ultimately find themselves enmeshed in the darker, denser, worlds of what we call the "Underworld" or "Hell" when they leave the Earth plane.
Some particularly strong-willed "rebel" souls have attempted to create their own self-dominated worlds separate from the evolutionary plan of the Creator. They seek constantly to gain power and advancement through the enslavement and perversion of those weaker than themselves, and through this process they create dark, twisted worlds, cut off from the Worlds of Light. Within these fortified worlds of their own creation they remain as undisputed masters.
These dark and negative souls, collectively known in the occult world as the Forces of Darkness, are masters of a body of planets and peoples in our universe which are constantly seeking to take over and control weaker worlds. In the distant past they have been partially successful in taking over Planet Earth and have since remained as a powerful force in the background, using their dark influence as the power behind various oppressive regimes and self-willed leaders to promote wars, conflict and oppression