Here again, the facts do not deliver the conclusion. A diversity of ethical and religious beliefs hardly insures that they are all somehow true. Ethical relativism eliminates the notion of a moral mistake. But this is just as fallacious as saying that every answer on a multiple-choice test is correct because there is a diversity of answers. There may also be less diversity between cultures than is often thought.
Every culture has taboos against stealing.
Yet a desert culture may penalize the theft of water much more highly than would a tropical culture. As Paul tells us in Romans 1-2, God has endowed with a conscience all those created in His own image, however much we efface or neglect it. Relativism also leads to absurd conclusions which undermine its credibility. If there is no true moral law that applies transculturally, then there is no basis for one culture to condemn actions in another. Surely any morally sane person must ethically condemn Nazi atrocities as evil and praise the heroes who resisted the Reich by saving Jews from extermination.