morality is subjective?

I think intellectually, personally, logic and overall perspective of life is highly esteemed in the favor of the atheist. But as far as morals are concerned they must be divinely inspired, otherwise we are only living by whatever idea of “right” and “wrong” we were brought up believing. Which is a bunch of rubbish, because I could do whatever the hell I want. My fear of man is the only limitation to the caliber of depravity I wish to invest. If we behave and act like animals, why does the world get all bent out of shape when human beings go on these mass murdering sprees? they do this because we are brainwashed into believe that we are animals.