There are many outlooks on life and our existence. What our purpose may be may still remain unknown, but there are common beliefs. Just as with our existence, there are several thoughts on the definition of evil. What is evil? Evil could be many things, but a few of them are obvious. Evil could be matter, energy, or a void.
By saying evil could be matter, it's observed to be real. Matter is what we walk on, breathe, eat, and taste. Evil could be what most would call a devil, demons, or other people. If evil is matter, it walks around us and interferes in our lives. You cannot see it or hear it, but you can feel it.
If evil is energy, it's not just something moving around us, but inside of us. Energy is not massive; it has no size or density. Energy is that which flows through matter. Energy is what we do or observe. The most prominent belief is that evil is an energy that affects those which it flows through. So where does this energy come from?
Einstein explained evil as a void. A void is the absence of energy and matter. Just as silence is the absence of sound, darkness is the absence of light, and cold is the absence of heat, evil could simply be the absence of good, a void between good energy and good matter. This does leave some speculation though. If evil is a void, then it is not an opposing force, but a neutral one. In this sense, evil does not exist. It explains why evil is so overpowered by good, but it leaves much to be understood.
Without a method to test evil and determine where it originates, how it reacts, and where it is, we are left to speculate. Perhaps evil is all of these things. Perhaps there is a single entity emitting an evil energy that fills the void where there is no good. Whatever you may believe in, put effort into understanding it.