Good Vs. Evil

The idea was brought up in my Philosophy class a few weeks ago. My professor insisted that you could have a world where everybody could be inherently good. It would be a perfect world in which no evil would exsist at all. He also put this burden on a just and ethically good God and argued that because this world has evil in it, and God would have the power to remove it, he is an evil God.
I have a major problem with this. Not because it is stating the possibility that God is evil, but because it is ignoring something that is essential to our way of life: Evil. Good cannot exsist without Evil. If you had that world with only "Good" it would be perfect, but it would not be good as there would be no way to distinguish your actions. It would simply just be.
Alright, here's some definitions from dictionary.com associated with Good.

Morally excellent; virtuous; righteous; pious. (I believe this is essentially what good is all about, though I believe it should be noted that it is a CONCIOUS CHOICE to be the following, which is a big part of being "Good")
Satisfactory in quality, quantity, or degree (Okay, so my book with the bent spine is not good, therefore by being the opposite it is bad and to a larger extreme evil?)
Well-behaved: a good child. (So, am I an evil person if as a child I may have been prone to terrorizing my brother and was disciplined as a result therefore learning right from wrong?)
Kind, beneficent, or friendly (There are many people I have meet that are none of these. Does that make them an evil person?)
Honorable or worthy (In whose eyes? This is a matter of opinion; It's hard to judge someone's worth and far to pretentious to have it be used as a quality of Good. Was Hirohito of Japan during the second World War not worthy? And yet spitefully evil in the treatment of the Chinese and the authorization of the bacteriological research unit? Honor and Worth depend on your personal point of view, nothing more.)
Educated and refined (So if someone doesn't get a college education....are they evil?)
Financially sound or safe (Poor people and minorities must be evil than. Damn those filthy hobos, I knew they were Satan's pawns!)
Genuine; not counterfeit (So disregarding the fact that when you are young and impressionable you're still trying to figure out who you really are and may conform with ideals and behaviors that aren't really you, you are essentially evil?)
Reliable; dependable; responsible (Fair enough, but I never thought of irresponsibility as evil. All of the shamed Germans who are being held responsible even today for the monstrosities caused by the Nazis and their pretense of doing nothing whatsoever about it does not scream villianry. Oh, I dunno, perhaps they were simply afraid? Does fear constitute evil?)
Healthful; beneficial (All those kids who are terminally ill must than be evil.)
Not spoiled or tainted (I wouldn't necessarily call all those spoiled brats who whine and cry for a candy bar evil. They just haven't been taught any better.)
Cheerful; optimistic; amiable (Don't be sad or you're evil guys.)
Attractive; handsome (This is just ridiculous. I'm not even going to bother with it)
Conforming to rules of grammar, usage, etc. (Hahaha, I actually love this one. EVIDENCE THAT TWILIGHT REALLY IS EBIL!)
Best or most dressy (Dumb.)

Okay, now that we have navigated past the wall of text...
The point of showing all of those definitions was to prove that Good is merely the other side of the spectrum. Every single definition above has an opposite. What does this mean? IT MEANS THAT IT CANNOT EXSIST WITHOUT THE OTHER SIDE. None of these things could be unless there was an example of what it isn't. Reliable-unreliable; Healthy-unhealthy;Cheerful-uncheerful; etc. So that perfect world where there is only good is impossible because good is merely the idea that is opposite of evil, and without it, it cannot exsist. I feel like I'm repeating myself, but I'm not sure I'm getting my idea across as well as I would like. Moving on-

Now, it's important that this last part is not misunderstood, but I believe that not only is evil necessary but it is good for us. When we have evil, we are able to learn and build ourselves against it. People fight to be the best person they can possibly be (Without simply being such >.<) We make the choice. The ability to do such is far more powerful than the outcome because it is a freedom we could not have in the all good world (If it could even exsist). I also believe that evil is essential for beauty. Without evil, such wonderful things as compassion, loyality, etc. would not exsist. And if everything in this world were perfect, if we saw a waterfall, or trees in the fall, or fresh fallen snow, they would be nothing out of the ordinary and we wouldn't even bother calling it beautiful. We need evil in this world, I wouldn't want to live in a world without it. With evil, I get to make the constant choice to act against it, which gives me a fulfilling exsistence in life where I am not simply living it, but creating it.
Whew, how's that for brain vomit?