I'm being nice by not talking about what's between the lines...but since you asked...
"what many saw as a clear demonstration of unredeemable and deep-seated malice, these researchers interpreted as more, in the words of Hannah Arendt, 
banal."
Between the lines...they're saying that you don't need a supernatural explanation for evil.
"This grounding of evil in ordinary, as opposed to extraordinary, phenomena have led some to describe the notion of “pure evil” 
as a myth."
Again, this is saying that the notion of Satan creating evil is almost silly.
"A misguided understanding of human nature deriving both from specific socio-cultural traditions as well as a general tendency to understand others’ behavior as a product solely of their essence, their soul, as opposed to a more complicated combination of environmental and individual forces."
This is basically saying that if you think people do evil things because of Satan...you're wrong.
"How can we measure people’s belief in pure evil (BPE) and what consequences does such a belief have on our responses to wrong-doers."
So, the rest of the article goes on to describe how the belief in Satan and pure evil affects behavior and judgement...and surprise, none of it is good.
"BPE predicts such effects as: harsher punishments for crimes (e.g. murder, assault, theft), stronger reported support for the death penalty, and decreased support for criminal rehabilitation."
Basically, this is saying that the research shows that belief in pure evil (BPE) results in judgements that are less forgiving, understanding, and generally more harsh towards people.  Not good things.
"Follow-up studies corroborate these findings, showing that BPE also predicts the degree to which participants perceive the world to be dangerous and vile, the perceived need for preemptive military aggression to solve conflicts, and reported support for torture."
So basically, if you believe in Satan and pure evil...you're probably a worse person than someone who doesn't, in many ways.
"The longer we cling to strong beliefs about the existence of pure evil, the more aggressive and antisocial we become. "
This is saying that, over time, the longer you believe in supernatural causes for human behavior, the more poorly you will likely treat people you see as "evil".
That's a quick breakdown of what the article is saying "between the lines"...I didn't really want to open up this whole can of worms...but you seem intent on claiming that it says something it doesn't say.
Why you keep claiming this, beyond your own pride, I have no idea.  I read the article...I'm hoping that by now you've read the article...and really anyone else can read the article...so really, we can all see that it doesn't support in any way your claim that belief in Satan is somehow a good thing.  All the research shows that it clearly isn't.