AGW denier and generally right wing oriented contrarian Matt Briggs thinks atheists have a "problem" with evil, but I agree with commenter lucia’s first sentence:
Matt, Your very first claim is nonesense: "Evil is a problem for atheists because, for them, it does not exist absolutely”
Lucia bases this response on the claim to be an atheist who does have a definition of absolute evil, but my reasons are different from (in fact in a sense opposite to) lucia’s.
I don’t know if I qualify as an atheist, but for me good and evil do not exist absolutely – and for me that is not a problem.
So far as I have ever been able to tell, “good” and “evil” are just words used by people to label certain behaviours that they feel compelled to encourage or (resp.) discourage (usually on the basis of effects of such behaviours on the perceived welfare of the family, tribe, or super-tribe, rather than on the immediate well-being of the individual); and they tend to have the desired effect by virtue of being connected to approval and shaming since infancy in a brain which evolved over many generations to manage the behaviour of a social animal so as to be successful in its context by responding to approval and shaming signals from its peers.
Certainly Briggs' demand for a definition was odd since the obligation to define a word must surely fall on the one who uses it. But on further reflection I am tempted to actually use and define the word "evil" as something distinct from merely "bad". Because, for all the risk of harm he brings to the world with his denialism, I would be inclined to say Briggs, though maybe "bad", is not "evil" . And the reason I deny him that label is because I don't suspect any real wish to hurt others in his vainly posturing behaviour of picking holes on the arguments of AGW advocates and left-liberal politicos rather than seriously considering the overall picture. So I suppose that it is malicious intent - or any other kind of deliberate overriding of the dictates of conscience - that underlies my own conception of evil (something like what the religious might describe as knowingly making a pact with the devil).
So it seems that for me the distinction between "bad" and "evil" is a matter of intent. But, as usual with words, there is a shading of meaning. We might consider a person who cannibalizes children to be evil even if he was a psychopath without conscience (though perhaps less so if we knew he was delusional). I think though that the reason for this is more out of inability to imagine the truly psychopathic state than out of really extending the definition. (After all we probably wouldn't use the word evil if the psychopath were replaced by a baby-eating lion).
So perhaps I do have an absolute definition of "evil" as deliberate action contrary to the dictates of conscience - even though it is one I cannot ever truly test with regard to another person because I don't have access to their internal mental processes. Despite that untestability, the evilness of any particular act is either true or false independent of the observer (though not the actor). But then being evil is not a property of the act itself but rather of its relation to the conscience (or perhaps to a religious the "soul") of the actor. So even though the definition of evil is absolute, the evilness of a particular action is relative.
Of course, if I am going to suggest that Briggs, though probably not evil, is maybe "bad" then I guess I do need to say what I would mean by that as well.
Even though I do use those words I do not have an absolute definition of “good” and “bad”, but as I said before, for me that is still not a problem.
When I say some action is “bad” or “wrong” I am merely expressing my own feelings and I do not believe that anyone else’s such assertions have any more absolute (ie observer-independent) content than my own.
This does not mean that discussions of ethics (and aesthetics) are pointless, but logical argument may play only a small part in them. How we feel about things influences our behaviour and my own sense of ethics does not rule out trying to persuade others to change their ethical and aesthetic positions. Since the object of such arguments is more to change feelings than opinions I have no objection to the use of appeal to emotions in such arguments. (The only problem is that if it’s so blatant that the manipulative intent becomes clear then it might not be effective.)
Note: Really this wouldn’t have been be a bad post if Briggs could only suppress his tendency to throw in egregious straw men at every opportunity. It’s especially discouraging when he raises a topic about which there might be some interesting things to say which get smothered and lost in the overwhelming mass of “cleverly” inserted straw.