Joel Marks:

It seems to me that what could broadly be called desire has been the moving force of humanity, no matter how we might have window-dressed it with moral talk. By desire I do not mean sexual craving, or even only selfish wanting. I use the term generally to refer to whatever motivates us, which ranges from selfishness to altruism and everything in between and at right angles. Mother Theresa was acting as much from desire as was the Marquis de Sade. But the sort of desire that now concerns me most is what we would want if we were absolutely convinced that there is no such thing as moral right and wrong. I think the most likely answer is: pretty much the same as what we want now.
For instance, I used to think that animal agriculture was wrong. Now I will call a spade a spade and declare simply that I very much dislike it and want it to stop. Has this lessened my commitment to ending it? I do not find that to be the case at all.
That’s why I’ve never had any legitimate use for the term “evil”, except as joking hyperbole. It’s an attempt to give metaphysical weight, transcendent backing, to an all-too-human perspective. It disingenuously smuggles in an assumption that there are certain thoughts or deeds so foul and abhorrent that they rend the very fabric of the universe with their wrongness, adding a dissonant note to an otherwise natural celestial harmony. But “right” and “wrong” only make sense in the context of a shared language of common values; they are not independently existing categorical absolutes. Support what you will, oppose what you must. But your only strength lies in numbers of like-minded believers. The universe itself doesn’t care.