Hmm.
Evil.
Good vs Evil.
I think that our human position makes it very difficult to be objective about our own position between good and evil, and even the position of others. It does seem apparent on the really large scale that Nazi Germany as an entity perpetrated a lot of evil acts, and left a legacy of evil in the world by ramping up antisemitism, nationalism, racism, and homophobia to amazing and hellish levels. We can say that Hitler was evil, but was he more or less evil making orders or policies than those at the lowest level actually doing the killing, the torture, the mayhem? And can we, from our human level, be sure that Hitler wasn't being directed by something more evil than himself?
My Christian self believes that today's Protestant mainstream has an interesting diametric going on in this regard. I know many people who stand in church, week after week, praising God and contributing to the Church and its work very sincerely. But a huge proportion of them are happy to say they believe in God, and in Christ, but will not admit (particularly out loud) that they believe that there is Satan at work in the world. In fact, those of us who are quite sure Satan is at work in the world are practically looked at like crazy people when we talk about the fact that everyone who believes should be in a constant struggle with their fallen self, that part of us that still reflects original sin, and is capable of Evil thoughts, words and deeds. All sin is, in fact, rooted in the deception of mankind and original sin, which was perpetrated by Satan in the Garden of Eden, and places us in constant tension and a state of spiritual warfare.
If Satan is a human construct, as so many seem to believe, how can God not be a construct as well? I have difficulty believing in God and the risen Christ in the absence of a very real enemy. Without Satan, Christ's suffering, death and resurrection, as fulfillment of God's promise to redeem us from sin and ransom us from death, becomes far less meaningful. Satan must be real for God to be real, in my opinion.
We are all capable of evil, and I have sinned plenty in my life, and that is partly a result( in my opinion) of evil at work in the world, and partly an unwillingness to look beyond myself and my own (perceived) needs. It seems to me that you are looking for stories of transformative evil, a deed that crosses the line that separates forgivable sin from unforgivable (in our human perception) sin. Of course, there is no unforgivable sin for those who repent and turn their backs on sin, at least to God. The world, however, is another story. The kind of deeds it seems you are looking for are the kind that we bury away forever, lock up in our own Pandora's box, the sort of thing that makes it difficult to look in the mirror if you have any kind of conscience. And some have rightly pointed out that those genies never go all the way back into their bottles.
If you had no conscience, though, perhaps you wouldn't identify those acts as evil in the first place...
Looking down at these responses, it's interesting to think about the words behind the words. I know for a fact that in our midst, there are criminal pasts, people with mental health issues, probably people who have been victims (and possibly perpetrators) of heinous (and evil) acts of exploitation and abuse. There may be people who made choices, like terminating a pregnancy or ending a marriage, or attempting to end their own lives who may have felt trapped in an untenable situation. I've made peace with my own past, with the person I used to be - it wasn't that hard, I never considered myself evil although I have, in the past, been pretty callous and occasionally cruel for no real good reason other than it was easier than being understanding or caring or kind. And I used to be a lot more impulsive about my own pleasures at the expense of other people's pain.
Maybe some level of Evil is our standard state and the transformative power is Good - I mean, in many cases it seems more of an effort for people to be kind. In so many cases, people are indifferent at best. But I like all of you enough that there is nothing you can say in this thread that would make me hate you. I just hate to have my illusion of all my perfect, well adjusted and highly functional message board friends shattered...