Is human emotions. Think about it. Fury, sadness, greed, vengeance, among others. They all push others to commit evil acts. Look at World War II for example. Germany was crushed, then Hitler took control of others emotions and pushed others to extremes. Thus war broke out. Even on smaller scales. People (see: girls) are very emotional. They stab each other in the back constantly because they FEEL threatened by others, when in reality nothing is wrong.
I would like to propose that to eliminate evil, we must eliminate human emotion. We must ascend and become robots. Science has proven to us through bioengineering that part of this process can be done in the form of mechanical limbs. We must push science to the limits, becoming completely mechanical beings with no emotions. No emotions means everyone gets along. Thus evil is abolished.