Somewhat surprisingly, I've noticed a trend of late that marks a convergence of two seemingly disparate philosophies: New Testament theology and post-modern relativism.
The convergence of these two traditions is not deeply philosophical in nature, but is found in an attitude that people take to be reasonable with respect to practical ethical problems. The idea is basically that we should not judge the actions of others. In the Christian tradition, the reasoning behind this is that God alone is the ultimate judge. From the relativist's perspective, there is no ultimate truth about which judgments could be correct.
As I've been arguing, I take most forms of relativism to be incoherent, and the most coherent forms of relativism (something close to nihilism) to be implausible and unacceptable. The Christian view I'm describing here, to its credit, is perfectly coherent. Of course, only some sects of Christianity emphasize this particular part of the Gospel, and you can find passages in the Biblical texts to support any range of moral view.
I think, for the most part, we should reject this view. We are entitled to judge others, and we ought to. We ought be humble in the extent of the conclusions that we reach from these judgments, but judge we must. For example, in my work with children with special needs, there can be times when I judge the conduct of other staff to be inappropriate or wrong. If I refrained from judging others in this way, I would be neglectful in my duties to protect vulnerable children.
We judge murderers and thieves to be guilty of crimes, and we judge judges to be competent in carrying out their sentencing.If we grow up in a religious institution, there comes a time when we must judge the quality of the instruction provided therein.
Judgement of others plays a valuable role in the development of our own moral character. When we consider the actions of others, the moral reactions we have can play a key role deciding which actions we deem worthy of taking. Often it is hard to maintain objectivity about ones own actions, so adopting the spectator's stance on the actions of others can fine tune our own moral judgment.
The motivation for the "Judge Not" crowd is clear. Morality has often been seen as an insider's game for passing on top-down judgments of worth from a domineering hierarchy. And this hierarchy has often been wrong, and with grave consequences. But the antidote to bad moral leaders is not to abandon moral judgment. We should instead open up the ethical dialogue and come to better moral judgments.
People, often well-meaning, liberal people, will tell you that morality is a private matter. Nothing could be further from the truth. Morality concerns how we should treat each other, and what reasons we have for acting towards each other in the ways that we do. It is inherently not a private matter.
So when, in a discussion about homosexuality, someone tells me, "I don't judge homosexuals because the Bible tells us that God is the only judge," I am not relieved. I think we can judge homosexuality, and judge it to be absolutely benign. It is absolutely appropriate to judge the actions of others, and if we have reasons for believing they are wrong, then we should not shy away from that judgment.
There are some caveats. The "Judge Not" view has some merit, as we should not be overly-zealous in our convictions. Though we may judge others, our judgements should always be tentative, and we should always be open to changing our minds. You might say that we may judge, but we should not be judgmental.
One way to do this is to focus on evaluations of actions, rather than people. Since we never know another person's entire history, it is best to reserve judgement on them as a whole. We can still judge them to be acting wrongly in certain ways, but when engaging people about this judgement, we should focus on the reasons that make the action wrong. This is more likely to garner a positive response, and less likely to offend (although, there's no guarantee on either count!). Interestingly, this is not unlike the religious dictum, "Love the sinner, hate the sin," though the context in which this quote is employed often renders it deeply problematic.
We should not heckle, harass, or accost people just because we think they are wrong about something. This is ineffective at getting the point across and offensive in its own right. There also might be times when, though someone has acted wrongly, belaboring the point will benefit no one. In these cases, we should keep our judgments to ourselves.
Nevertheless, we need not fear a robust dialogue about morality. It's the only chance we have of getting things right.