To your point about the need for contrast or opposites, then I ask, is there such thing as super-humanly good? What would the exact opposite or "opposing good" be to a satan-worshiping pedophile or a cannibal who performs ritualistic sacrifice of children? Even better, what's the worst thing you can think of that someone could do to another in this world, then conversely, what would the "equal and opposite" good be to that? Not to get too religious, but for me in my thoughts and experiences, it always comes down to Jesus Christ as the 'ultimate good'; the opposition to the most evil things in this world. In my researching, I've seen some evil stuff - evil is the only word that I can use to describe it - maybe even super-humanly evil.. So knowing there can be such evil in this world, based on the 'equal and opposite' principle, there has to also be such good as well, and that's what I try to focus on - the good.

In that vain, I agree, you cannot completely blot out the evil from consciousness - its needed so you know that there can be an equal amount of good in this world as well - it just becomes up to you which one you allow to exist in your conscious, and thus subconscious, and thoughts on a regular basis.