Why do people do evil? It is fairly clear that "evil" exists, and equally as evident that humans are capable of inflicting evil. So the logical question is "Why? What meaning is there behind people doing evil?"
It is, by no means, and easy question. Evil, by its very nature, is depraved of meaning. That is why suffering aches our hearts and minds so much: Suffering has no meaning, no matter how hard we try to say otherwise, there is no reason why people must suffer the way they do. Evil is chaotic and legion, it lacks direction and harmony and purpose. Evil is meaningless, because meaning flows from Truth. Things are meaningful when they exists in consequential harmony with the Truth omnipresent in God's Creation. When our lives sit harmoniously within Truth's cosmic scheme, they are resplendent with meaning, with purpose. It is this meaning that allows us to look upon our own smallness and scale it against the grandeur of everything and maintain our sanity. Evil, as previously stated and restated, is meaningless. It flows not from Truth but from deceit. So where then does the deceit come from?
People like to know things. Knowledge is power, not so much over others, but over ourselves, over our own existences. People are perfectly comfortable with those things that they know. Its the stuff we don't know that tends to scare the ever-living shit out of us. It does not take an astronomer or a philosopher to see that the cosmos is absolutely huge. The expanse of Truth reaches far greater than any man's ability to know it, even if he were given until the end of time to explore it. Truth is fundamentally Mystery, that is, its nature is to be beyond knowing, to supersede knowledge entirely. Its not that Truth doesn't exist, its that Truth is "more" than existing. (If you find this idea mind blowing, you're on the right track...welcome to the wonderful world of philosophy). We love to know the Truth, and yet, we do not know the Truth, we cannot know the Truth. We may one day come to exhaust the reaches of our ability to know,
and we will still stare into the face of Truth, ever mysterious, ever beyond. Truth is not known. Truth is believed in.
Critics seem to think Faith is an aversion to knowledge, a form of dishonest certainty keeps us from having to admit that we don't know. They seem to think faith is a lie, ignoring that which we know exists in favor of embracing that which we really really want to exist. This idea may be true for the "faith" of some, but Faith, real Faith, this notion could be no further from the truth. Real Faith is not undermined by knowledge; you can know as much as you please and then some and still have Faith. Faith exists where the human hunger for Truth and the human capacity to know Truth diverge, where knowledge fails to reveal the Truth simply because it cannot. Ultimately, we have to look out into the cosmos, into the farthest reaches of existence and ask ourselves if it is all coldness, darkness, and hostility, or if the Truth, if Reality Itself is something far kinder to us. There are only two possible responses: Faith and Fear.
Faith is asserting that Reality is Good and True and Beautiful, concepts not graspable by knowledge. Faith looks into what cannot be known and responds with trust, with a profound assent to Goodness which cannot be known to be. To be fair, there is no reason for us to have Faith, at least not from our end of existentialism. (Yes, I did just suggest a bipolarity to existentialism. More to come on that later...perhaps) As the anti-theist claims, Faith is illogical, because logic doesn't even begin to apply where and when Faith is required. Faith is not us discovering truths, but discovering ourselves in and through Truth.
If Faith is gazing toward unknowable Truth's face and trusting that it is, in fact, good and favorable to you, Fear is the exact opposite. Fear is gazing toward unknowable Truth's face and believing that it is unfavorable towards you, or worse: indifferent towards you. Fear is the fundamental realization that the person/thing/entity ultimately responsible for you and your well-being is you, that nothing out there cares more absolutely for you than you (and/or your loved ones, should you be so fortunate to love and be loved).
Fear prompts us inward, it sets our priorities to ourselves, our preservation, our own purposes and meanings. Reality is no longer our concern, because it is not concerned with us. Instead, we craft our own realities; microcosms in which we really matter and have a sort of meaning about our lives.
Ultimately, this results in evil. When we create our own, false realities of false truths with false meanings, we deceive ourselves. True meaning comes from knowing you are consequential and harmonious with Reality, deceit comes from a Fear-driven attempt to build a reality in which all things are consequential and harmonious unto you. Ultimately, this is a meaningless existence; it lasts as long as you force it to and only to the extent that you can make it exist.
Fear deprives our actions of Truth. It causes us to reject God, to reject the cosmic reality he created and our role in it, and robs it of real meaning. Why do people do evil? Why do they do things that are meaningless and cause suffering? Because somewhere in the vast depths of their soul, they are so very very afraid. Each and every one of us, every miserably ordinary sinners suffers from the same fundamental issue: like Adam and Eve in the Garden, we face Truth naked and afraid. We gaze into Eternity and are forced to choose Faith or Fear. This is the departure point of religion, and must be relived at every moment of every day, even if in the smallest of ways. Every day, we have to look at the world around us and resist the temptation to be afraid, to reject reality and make our own in the comfort of our mind. We must consent to Faith, to go beyond knowledge and assent to an infinite and eternal Truth that some how, some way, finds you meaningful and harmonious. Such is your square one. Go forth and Faith.