As I’ve talked to people about their beliefs over the past few years, I’ve been surprised to discover that belief in moral relativism is still alive and well. In fact, nearly every conversation I have on any spiritual topic seems to end up there eventually.
This is especially surprising to discover in a culture that is so adamant about fighting for social justice. C.S. Lewis explains why in his essay “The Poison of Subjectivism,” written during World War II:
Everyone is indignant when he hears the Germans define justice as that which is to the interest of the Third Reich. But it is not always remembered that this indignation is perfectly groundless if we ourselves regard morality as a subjective sentiment to be altered at will. Unless there is some objective standard of good, over-arching Germans, Japanese and ourselves alike whether any of us obey it or no, then of course the Germans are as competent to create their ideology as we are to create ours. If ‘good’ and ‘better’ are terms deriving their sole meaning from the ideology of each people, then of course ideologies themselves cannot be better or worse than one another. Unless the measuring rod is independent of the things measured, we can do no measuring. For the same reason it is useless to compare the moral ideas of one age with those of another: progress and decadence are alike meaningless words….
[E]xcept on the supposition of a changeless standard, progress is impossible. If good is a fixed point, it is at least possible that we should get nearer and nearer to it; but if the terminus is as mobile as the train, how can the train progress towards it? Our ideas of the good may change, but they cannot change either for the better or the worse if there is no absolute and immutable good to which they can approximate or from which they can recede. We can go on getting a sum more and more nearly right only if the one perfectly right answer is ‘stagnant’.
There can be no moral progress if there’s no standard. The moral relativist who is fighting for a moral principle is living in tension with his beliefs, but he likely has never realized it. That’s where you come in. Anytime someone advocates for justice or any kind of moral progress—even if you disagree with his idea of what justice and moral progress require—that is a point of contact you have as a Christian with that person. You both agree there are objective morals worth fighting for! Starting from your point of agreement, you can help him think through the implications of the existence of objective justice, pointing Him to the one who is the living standard and source of all that is good.