Balance exists in all things, without balance the scales would tilt drastically in either fashion. Use the cliche of Good and Evil, even if Evil were to be eradicated, then the existence of Good (designed to fight Evil) would be nullified. Without balance the fabric of things would be much different.
Harmony between opposites is inconceivable, as without the existence of one side, the other side cannot exist either. All things in the universe tie together, like a ball of yarn, if you pull one string, the rest soon begins to unravel.
If we are referring to a balance between nations and individuals, balance between people is conceivable, however, I believe the Human species is a barbaric one like any other we know to exist, and we will never be satisfied with basic existence among each other, (because we all strive to be number one, we compete with each other, which then furthers to conflict and feud.)
To my final point, I believe no acts are redeeming, and there is no final judgement, or divine intervention, or great retribution. There is no reason to be Good to other people, nor is there a reason to be Evil. You do not go to Hell if you are a n evil person, nor do you got Heaven if you are a Good person. So you ask to yourself, "Then how do I choose?", with free will, not with a church, or cult telling you which road to take. If you are only kind because someone said you should be, then where is the good deed, it no longer becomes a good deed, it becomes a linear choice and without proper reason and free will.