In the past I used to think I was "good" and righteous when I was so angry and full of hate that I wanted to murder who I thought were the "worst of the worst" kinds of people on this planet, like the war criminals for example and others who would ruthlessly harm and destroy innocent lives for their own pleasure and gain...

That is a very wise insight you can have about yourself. It seems to be the beginning of a path that you personally do not seek to ward off.
Man is all too quick to consider any newly discovered wisdom as "already understood and living by it" for himself, while he is perhaps still in the infancy of such great wisdom and must be careful not to pass on what he has learned to others. The wise, I hear again and again, are unwilling to share their "secrets" in this regard because the words are twisted in their mouths and made into weapons. So, they are not easy to find and not easy to understand.

Though, if you can learn to love everyone and not have anymore enemies to go fight and kill, then... Perhaps you will find true peace and you will find "Satan" less in your consciousness and existence.

I think that "love your enemy as yourself" should first be reflected back to self-love. Is it the case that the one who takes this saying seriously is one who can love himself at all? Do you love yourself?

Such love needs to be renewed and reminded again and again in every single encounter. The doctrine of Buddhism has a lot to offer for this.

The moment when one has defeated someone with words or deeds is not really a victory, because where there is a winner, there is always a loser, but both have lost. Unless the loser shakes hands with the winner with a light heart and admits that he erred. But if the winner does not consider the matter settled with an equally light heart, and only basks in the other's loss, he will interpret it as weakness on the part of the one who shows himself defeated. Therefore, if the competitors consider the contest a welcome challenge from the outset, they are already wise. In this sense, yes, I see the term "Satan" as one who is an adversary and you can either make the worst or the best of him. In mythology Satan is being seen as a fallen angel and acts from then upon as the great disturber between the other angels and god. Even god needs a counterpart :)

I recently saw a Formula 1 film in which Niki Lauda and James Hunt went down in motorsport history as rivals. They only hated each other on the surface, as it seems or the film conveys. But in their depths they appreciated the other as an opponent who spurred them on to superhuman deeds for themselves. You can say what you like about motor sport, but the proximity to death makes it a special kind of sport. Like any extreme way of dealing with life.

Great article, highly appreciated, also the comment section which I find almost even more worthwile to follow. :)