A tough question. And one that isn’t served by absolute definitions. It’s something that has to be judged, on a case-by-case basis.
It has a lot to do with context. The act of taking someone’s life, for instance, can be murder or euthanasia, depending on the circumstances. I think most of the examples you raised would be evil, except for “hatred” against a group. For me, only an action can evil, not an emotion. If that hatred is acted on, then it becomes evil.
The best definition of evil, for me, is an unnecessary act of cruelty. The “unnecessary” part is where things get messy, because anyone who commits an act of cruelty will argue “necessity.” This is where debate and discussion – the lifeblood of sane and conscious society – come in. This is why our societies have juries – the best way to understand if an act of evil was commited, or necessary, is take a group of emotionally-uninvolved strangers, have them hear both sides of the argument, and discuss it.
I believe human beings have an ethical instinct that helps us sort out these questions – most of us, seeing a murder, witnessing a genocide, would know, in our guts, that that is somehow wrong. We have some sense of the pain we create in others. But like any instinct, it can be repressed. We tell ourselves it was necessary, and this is sometimes true (killing someone in self-defence, for example). It may even help us to sleep at night. It’s even easier to rationalize when one does not see one’s victims.
People who commit acts of evil generally think of themselves as good people. Or at least they try to convince themselves of such. Hannah Arendt, in Eichmann in Jerusalem, discussed the “banality of evil” in the Nazi death camps – by bureaucratizing and systematizing the camps, and making each person who participated such a small part of the process, these people could convince themselves it was not really their fault.
I believe the best possible life is the ethical one. As such, I’ve tried to cultivate awareness of my actions and their results. But anyone can fail in this regard. We are all equally capable of playing our part in an atrocity, or an act of petty cruelty, and pehaps realizing our own potential for evil can help.
Religions and legal systems that try to set evil down into an absolute moral code are setting themselves up for a disaster. Context is so critical that it almost guarantees that someone following the code will commit and act of evil, sooner or later.