Try a thought experiment.
What if...
human actions of good and evil counterbalance each other? When a human being creates good from a desire, an evil is prevented. When a human will creates evil, some good is extinguished, or prevented from being realized by another human will. Most actions have some combinations of good and evil, but this is rarely perceptible to us as a complete understanding. It is hidden. On some occasions, this good is nearly imperceptible, like a smile or a courtesy. What if it was even a thought rather than an action? The movie Pay It Forward leaned on the idea of a concatention of good acts. We don't really know the complete effects of our actions on others, or the next other that passes along our good action. Maybe our evils, even our small ones, do the same thing... Be good.