Imagine all I had ever learned indicated STRONGLY that there was this god who demanded animal sacrifice (as much pain as possible), and that this was morally righteous behavior. I would be doing something completely strange to anyone else, but it would seem perfectly normal and right to me. I'd have no way of knowing what I should REALLY do, and I couldn't have ended up believing or behaving any better no matter how smart and inclined to do the right thing I was, because there were no flaws in the deception that were perceivable to humans.
Would it be my own moral flaw that led me to act that way? The experiences and information I perceived about the world were such that even the best of humanity would have been led to act the way I did. It was a test that was not possible to pass, unless I deliberately attempted to do what was wrong. So should I be punished for doing what I believed was right? Did I do right or wrong by mutilating an animal? To anyone else it was wrong, but to me, it was right.
Imagine EVERYONE ELSE in the entire world believed that animal mutilation was the RIGHT way. There would be a debate website just like this, asking the same question about morality, and I would give an example that turned out to be how things REALLY SHOULD BE. Nobody would know it's how things should be, except for me.
None of you readers are aware, but that IS the case (except flipped). Animal mutilation is right. I am the one person in the world with true knowledge of morality, and you don't realize that all factors you perceive in the universe are illusions misleading you. Indications that it is cruel to do something, and any logic you might see, are flawed and false. No matter how smart you are, you can still be wrong about this, and you still are, but you have no way to understand how that could be, so I understand why you would disagree, but I personally know information that WOULD CONVINCE ANYONE with absolute certainty. I just have no way to convey it to you.
How do you know I'm not right? You're only deceived by the illusions. You can't know whether what you're seeing is the way things truly are. You might cite religion as support for kindness to animals, but all that taught you to believe in your religion, and that taught you to believe your religion supported animal kindness, was wrong. I know with certainty, whereas you are deluded into believing you know with certainty. How can you support any argument when I could tell you the support was more delusion? There is no way to verify morality, in any way.
Does it only matter that we do what we believe is right? Is that the true standard of right and wrong: doing what we think we should? Then morality IS sorta fickle..
What was considered socially and morally acceptable thousands of years ago is now frowned upon by a majority of modern society: women from biblical times to the beginning of the 20th century were viewed as property and had no legal rights. They were expected to be obedient to their husbands and had no voice in society.