Two sides of a coin

You may have noticed that many things in life have the proverbial "other side" to them. E.g., the Amazon rain forests have a positive effect on the Earth (they give back life-sustaining Oxygen, inhaling the greenhouse gas Carbondioxide, thus regulating its temperature too), but chopping them down for money assures livelihood for a lot of people; America invades Iraq for, allegedly, oil interests, but then a dictatorial government is only one step away from a Hitler-ian situation; one should have tolerance towards other people's mistakes, but the saying goes "the only thing that's required for evil to spread on earth is that good men do nothing"; "it doesn't matter whether you actually were able to do something good, it's the intention that counts" vs. "Actions speak louder than words" or even "Hands that serve are holier than lips that pray". The list is endless, and this post would quickly become too lengthy if I were to go on and on.

The point is, we live in a world of duality, and almost everything can be argued to have a negative side to it. What are we to do? How do we reconcile the unmistakable evil that we see around us with a good and compassionate God? Is all this duality, like the Vedas say, only an illusion? I'd like to know, with certainty!