In textbooks, this theory of human action is labeled "relativism." It holds that the rightness or wrongness of behaviors is relative to each person's individual opinion or to the social custom of her time and place. Stated negatively, it holds that moral truth is not the same for all people. Everything is up for grabs.
Relativism became palatable and eventually gained the upper hand because of its polar opposite dogmatism. There have always been individuals or groups that are willing to dictate beliefs and behaviors to others. These dictators, tyrants, and authoritarian parties claim to know what is true and yield to no request for proof. It is true because they say so! Questioning is simply not allowed.
But a strange thing happened on the road to non-judgmentalism and tolerance. All points of view came to be tolerated except the one which holds that truth and falsehood are real categories, that some acts are good and others bad.
Faith may have suffered the most in this great cultural shift. About the only thing that will not be tolerated in today's super-tolerant world is a Christian claim to truth or the public presentation of one of its moral claims. So "God exists" is allowed as a private belief; it just can't be offered as a public truth. "Lying is evil" or "fornication is wrong" may be held as a private standard; it mustn't be stated as a norm by which character is examined.
Ironically, there can be no genuine tolerance unless one is committed to a strong view of truth and morality. You don't "tolerate" people with whom you already see eye to eye. You can only "tolerate" those with whom you disagree.
Authentic tolerance means treating someone with fairness and respect even though you disagree. It means extending to others the right to disagree with your beliefs. More than that, it means trying to see the other's point of view and granting anything of value it captures. It means being willing to offer support for your views, not simply asserting something and expecting others to accept it on your word; it means listening to other points of view with fairness. Respectful discussion produces understanding. It even leads to changed points of view.
So don't apologize for having an opinion or a strong belief about something. Don't be intimidated when someone calls you an old stick-in-the-mud (or worse) because of your attitude toward promiscuity or cheating on taxes. Jesus never said it was wrong to make ethical judgments, only that we should not judge carelessly. Don't be so open-minded that you let all your common sense fall out.
"Stop judging by mere appearances," Jesus said, "but instead judge correctly" (John 7:24 NRSV).
And he was not being a bigot when he said it.