Let's say a society, past or present defined torture for pleasure as good. Would they be right or wrong to do so?In human history very few things remain constantly viewed as "evil." I cannot define good and evil in the same way that I define heat and cold. That was my point.
Contrary to what you say, in human history certain things reman constantly viewed as evil. Our perspective may distort that however. For example, even cultures that held to human sacrifice, didn't view murder as good. They saw their sacrifice as serving some greater good. That doesn't mean they lived in total anarchy from day to day. We can look back and KNOW for certain, they were wrong. But how?
Same goes for those who jailed and executed suspected witches. They believed witches to be real. And if they were real, and were actually doing the things they were accused of, then they would have been right to bring them to justice.
As with any analogy, they all fail at some point. That is why they are analogies. heat is not perfectly analogous to morality. However, there would be no way to measure cold apart from a source of heat. And there would be no way to measure immorality without a standard of morality. That doesn't mean cultures don't subjectively interpret and define. They do. And they often get it wrong. But, to say a culture was or is wrong requires more than another subjective opinon to do so.
Now, I would agree with you that evil isn't simply the absence of good. It does stand on its own. Man is able to 'create' his own calamity and bring on himself and others evil. There is still an analogous correlation, as man always has the option of doing good. You could say evil results from the failure to do what is good. The Bible says it this way, "Anyone, then, who knows the good he ought to do and doesn't do it, sins." (James 4:17)
Suffering in the world is where so many get it wrong. For one, how does the Atheist account for 'suffering and evil?' In fact, how could you even rightly call it evil. The Atheist has to smuggle in obejctive morality in the attempt to impune God's goodness.
Suffering and evil are not the same. One can rightly say that if man always chose good there would be no evil. However suffering would still be an issue. But even suffering loses any meaning in a material world. The conclusion, for the Atheist, is that God does not exist, yet they are still left with a world in which suffering and evil exist. Yet, they have no objective grounds to complain or resist either. Hitler attempting to irradicate Jews can be no more 'evil' than white blood cells attacking a virus.