If you see good and evil in the same terms as heat and cold, and also light and darkness, I think the answer becomes clear.
There is no such thing as cold, really. Heat is a form of energy...and cold is a word we use to describe THE LACK of that energy.
The same with light: darkness does not actually exist. There is light, and there is the ABSENCE of light, which we describe with the word darkness.
There is goodness...for we know that every good and wonderful thing comes from God.
And there is the absence of goodness.
Also, it is not uncommon for us to simply look at the random things that occur in our lives that we find unsatisfactory and immediately cry out, "Why am I beset by evil?" Just because something happened to you that you don't like doesn't mean that you are afflicted. If you want to see affliction, read the book of Job, yo. But Christ, Paul, and Peter (I think) all promised us that if we followed Christ, we would face trials. That's something that I think a lot of Christians miss - they think that putting their faith in Christ releases them from hardship, when that is NOT the case! Christ flat out GUARANTEED we would be taken through trials constantly, and our dependence on Him doesn't free us, but rather, gives us the strength to persevere, when we would succumb alone (Philippians 4:13, anyone?)!
Why do seemingly random people suffer? Look to the Old Testament: why did the Isrealites suffer? I'm not talking about the bondage in Egypt...if you listen to the Isrealites talk about it, slavery in Egypt must have been wonderful, because they were constantly complaining about having left and wanting to go back. They refused to acknowledge and respect the Lord who sent them into trial (Egypt) to strengthen them (they came out as an army that, whenever they sought the Lord, were undefeatable!), then redeemed them from the trial, and even when given manna and water from rocks, they grumbled and moaned. Sometimes the sons suffer for the sins of the father (father in the Jewish sense, meaning ANY forefather), as evidence when David had to hang all of Saul's descendants.
To those that do not know the mercy and grace given through Christ's blood, Yahweh is a pure and just God, and before Him can be no blemish. If He is the Light, then there can be no darkness. Imagine creating something you loved so very much, but because it's selfishness, it could never withstand your total purity, and it would forever remain separated from you, despite your love for it, because you are the light, and in it's freedom, it chooses the darkness? Always amazing how God makes a way for us to choose to turn from the darkness so that we can be with Him.