• Evil is self-reinforcing delusion.
• Delusion is persistent illusion.
• Illusion is false interpretation.

Thus evil is self-reinforcing persistent false interpretation.
Evil is the opposite of truth / reality. It leads us to dwell in a dream-world that we mistake for reality. When we act from that delusional perspective our actions are out of alignment with reality. Hence evil results in suffering and eventual destruction.

Nobody sets out to "be evil", those who you consider to be evil do not see themselves that way, and they may see you as evil. Each is doing what they believe to be right within the context of their delusions. Hence "the road to Hell is paved with good intentions".

Naïve realism (http://bit.ly/duT3V9) is the root of all evil because it is the deepest most fundamental misinterpretation of reality and thereby the root of all delusion.

The first comment below contains some quotes from the Lankavatara Sutra (http://bit.ly/azCaUY) regarding evil, delusion, naïve realism, reality and insight...