Morality in of itself is completely opinion based. What one person could see as a horrid atrocity another could see it as a complete justifiable and morally correct action. For example, killing a person would normally be seen as immoral but if you killed a person to save others most people would see that as a complete moral acceptance.
What you have to remember is that everyone is perfectly well adjusted to the environment (society, culture, religion, background) they have come from. There is no such thing as good or bad, moral or immoral. There are only conflicting value systems.
If you were raised in Nazi Germany and Nazi propaganda against the Jews was your only experience (along with the rest of the Nazi propaganda) in life, then you would become a Nazi. You would hate Jews. And killing them would seem the right and normal thing to do. And when someone came along and said 'Jews are just people, too!' you'd be accused of being a Jew Lover and treated with the same hatred. People tend to reflect the environment they are a part of and if that environment is twisted or distorted in its values, then the people will reflect that. Genocide is not considered moral according to ours or my value systems, but to the value systems of a Nazi German, it's simply normal.
In Ancient Maya, child sacrifice was commonplace. The children were often drugged beforehand, too. Now if you had grown up with them and that was your only experience of life, then all of that would seem perfectly normal to you. And when someone came along and said 'Hey, that's wrong to do that!' You're not going to say 'You know what? You're right!' You can't say that because you don't have any counter values or influences that allow you to look at it from that point of view.
If you went to a tribesman of the Headhunter Tribe and say 'Doesn't it bother you that you've got ten shrunken heads?' He'll likely say 'Yes. It does! My brother has twenty!' Is he immoral? No, he's perfectly well adjusted to his environment.
Human beings, like all creatures, are responding organisms. That means you respond to stimuli. If the stimuli is managed or corrupt or distorted in some way, then the responses in human behaviour will reflect that. There's no getting around it, that's just the way nature works.
So how did we get the near-univeral moral of not stealing and not killing? Simple. Conditions in the early tribal state of man. During those times tribes often had to pull together to get work done. A vast group effort (this is also the foundation of human social systems). When one tribesman killed another, or stole his food, this meant that that tribesman was no longer available to help the group and placed extra burden upon the rest of the tribe. So laws were made. Don't kill. Don't steal. In order to minimize the amount of extra work that would be placed upon the rest of the tribe otherwise.
I grew up being taught that morality is absolute, and absolutely clear to all. There are many people who believe this, and I am surprised that none of them have posted on this topic, yet. I will do so in their stead, and I hope to faithfully represent a common argument for the brand of moral absolutism I was raised with.
Consider the following:
Morality is not squishy or up for interpretation. All choices are moral, immoral, or amoral.
Most choices are amoral. There is no morality involved in what flavor of ice cream to eat, etc.
The remaining choices are starkly and obviously either moral or immoral. God puts recognition of this in our hearts so we can all always recognize right and wrong, and act accordingly.
Point of view does not change what one knows, but rather which particular aspects one sees, and how those aspects relate to their context. . It does not mean that whether we think an act is moral or immoral changes with point of view, but rather that our perspective of how the morality or immorality of the act relates to the world may change.
The attempt to argue that one’s point of view (preference, philosophy, belief, or world view) affects one’s moral sensibilities is misleading. The conscience still tells us when we are pretending that evil is good or that wrong is right.
Therefore all choices that are not innately amoral are obviously moral or immoral regardless of point of view.