All morality is subjective, including religious morality. Some religious people have deluded themselves into thinking that their subjective opinions about morality are somehow objective because they get it from a book that men wrote or proclamations from men of religious authority.
Societies are built on basic rules of morality to enable them to function. That's why we have laws. The most basic are not to murder and to respect the property of others. Otherwise, there would be chaos and society would crumble overnight. We all have to agree to certain rules that limit certain actions in order to facilitate the functioning of our society. Evolution has also built in certain things into us that make this a bit easier, as we are social animals. Most of us don't like the idea of killing another member of our species and that action tends to result in a lot of psychological damage, unless one is a psychopath.
Then there are societies such as the Third Reich where the state is opposed to the personal freedom of others and functions as a organic being fighting for its own survival itself. So you have the state deeming some as being enemies of the state that must be eradicated. In the Third Reich, it was the Jews, communists, liberals, anti-Nazis, etc. - anyone who wasn't able to be assimilated into the state's perceptions.
On an individual level, we each must choose what action is right or wrong for ourselves. It also depends on the worldview you hold. Some people have more authoritarian worldviews and so do not value individual freedom and will fight against it in some ways. Others value individual freedom and will fight against authoritarianism. But both must factor in the proper maintenance of a society. Only a small minority of people would actually want violence and mayhem to run wild. They usually commit crimes and end up in jail or dead. So we also have to factor in our personal well-being. Do you want to pursue a life that could land you in jail with your freedom taken from you, or even dead? If not, then you have to choose a path of action in life that includes basic respect for the law.