Which is confusion (stupidity) and evilness. And evil can be done knowingly or unknowingly. When you're confused, it's acceptable because they didn't know any better. Doing it with full understanding is another matter. I tend to stay away from both cases since I do not know which is ignorant or which is knowledgeable. I assume evil is evil, and leave it at that. But, some people just don't know any better. And to protect myself from being like them, I stay away. I don't try to change them, nor teach them, I just pretend they aren't there. From a logical standpoint, you counter evil by doing the opposite (good), and not by turning a blind eye. I believe the real risk is that, observing evil for far too long, you end up copying its traits. One would never do it by himself, but if that's all he sees, at some point corruption starts.
I observe a lot of things. Things I do not like, things that the break the writings of the bible, things that are unworthy of faith. And no one does anything about it. Neither from the outside or inside. Change comes from inside, and people do not change. Observing all this evil, at some point, one can confuse good for evil, and evil for good. You can turn away a genuine person because of confusion. But the inverse is also true: you can help an evil person. That's the thing about falling: you don't know you've fallen until a certain threshold is reached. And even when that threshold is reached, when you have nothing to compare it to, it's even more perilous.