Evil behavior cannot be justified. It can, however, be forgiven. It isn't always, but it can be.Of course, evil can be forgiven (thank God), but Luis has taken issue with me even referring to evil leftists as evil when it's a perfectly Biblical word/description. That's just bizarre to argue that people (OR behavior) can be evil but you better not call them that. How PC of him.
Just a word of caution, though: With God, all things are possible, so even evil can be stamped out, and those who engage in it (all of us) can be redeemed. I would use extreme temperance when labeling, or giving the appearance of labeling, anyone who you hope to convert as "evil." No one consistently engages in behaviors or philosophy with the understanding that the behavior and philosophy are evil. You might be able to convince them that the behavior is evil, but their hearts will harden in an instant if you describe them as evil while doing so. Some people, obviously, will never be able to see the distinction.
In my opinion, offering Hope will do a lot more good. It will take an act of God, though, to make a real difference. Let's pray he gives us a shot and gives us the wisdom, strength, and courage to do it right.