Moral relativism is interesting, is it not?
Each of us has some type of moral compass under which guidance we conduct ourselves from day to day. When people join in a community or society, they often share many of their moral "values." Those in the community who do not share a particularly strong value are often subjected to the others' judgement. Often, over time, these values are codified into laws, such as "Thou shalt not kill." Those that are not often evolve into the mores and folkways of a given community which can be just as strongly a part of the members' lives as those which are "legislated."
On a large scale, when one large group decides another group is "wrong" because the groups disagree about a point on their compasses, wars can be started.
On a smaller scale it becomes more personal. How often do we say someone is wrong, offensive, or shameful, not because that person has caused anyone harm or damage, but because they have triggered something on our own compass?
"You are wrong because you have offended my personal moral relativity!" And so, we project our beliefs onto others, without regard for theirs.
Humans are a funny bunch, ain't we?
AnnieLee