Here are some of my views and experiences:
Good and evil are moral constructions, made by men. It is both sides of one coin (as we say in Germany).
It is just a point of view. The “real” evil guy will not state himself as evil, but as good. If someone calls himself evil then it is just a role, a game, a provocation.
I think in the very end there is neither good nor evil.
A few years ago I had to meet a demon. I asked my spirit mentor if I am ready to fight it. He told me: “No. If you begin to fight, you already lost the fight! Stay calm and be sympathetic with the demon.” It was an important lesson for me. I found out, that this demon was just at the wrong time at the wrong place, called by someone who didn’t know what he was doing. It was not evil, but a stranger.
(In the greek mythology the original demons were not automatically evil, there were good and evil ones)
I would never call someone or something as “absolutely evil”. That is an arrogance.
Please do not misunderstand me: everyone makes his/ her own experiences. If someone faces something evil, it will help on his way to grow and expand his consciousness. Everyone gets a piece of the puzzle and in the end we get the whole image. Every experience is important.