How do you explain color to a blind person?
Unless they have seen, you can't even explain what sight is.
Explaining sight ends up with people who can't tell the difference between a picture and seeing it yourself. (as a metaphor)
Describing colors... there just isn't any concepts that you share to get it across.
Thus describing evil, first you have to describe the world.
And since most people have been lied to about the world their whole lives, its really hard to explain, requiring many layers.
Like above, i mentioned the shooting of someone.
Most consider that evil.
But, from a viewpoint of the wheel of life, it is but a step in a larger journey.
So, it is not really evil.
Many bring up the trolly problem to talk about what is evil or more evil.
But again, this is a mental game that has no bearing on real life, and thus no bearing on evil
(the trolly problem can't happen in real life because the world doesn't work that way. It can only exist from evil people trying to break your brain. Here, choose bad ending #1 or bad ending #2, and since you chose, you are bad, bwaahahahahaaa)
So, all i can really do right now is state that EVIL exists, and point out signs to look for.
Holographic universe type stuff, yeah?