I've had occasion to rant about this in a private forum, so it's worth putting a slightly edited version onto the public record. It encapsulates a lot of my basic thinking about moral philosophy.
The first thing is, I don't think there is such a thing as objective value. I can't even imagine what such a thing would be like. There are things that we value, and some kind of explanation can doubtless be given for how it is that we came to do so. That explanation may be partly Darwinian, partly historical and cultural, and searching for it makes a good research program, though not one where it will be easy to obtain a convergence of results (the relevant data is too gappy and too open to interpretation). But such values are contingent features of our psychology. Because we value security, for example, we have Hobbesian reasons to construct morality. Because we are responsive to each other, we have Humean reasons to construct morality. We have reasons that relate to what kind of life most of us find satisfying and see as "flourishing", giving us the kinds of reasons that virtue ethicists emphasise. And so on. But if we start off by thinking that there has to be some "objective value" in, say, the continuation of the human species we'll get things backwards. There is no such objective value. A psychopath or an intelligent alien or even a deep green environmentalist may fail to value it in the slightest and yet make no intellectual mistake whatsoever. Fortunately, from my viewpoint, not many of us fall into those categories.
Morality is made for us, given the things we actually do value. We are not made for morality or to serve any spooky "objective" values. There is, however, plenty of room to explore how much intersubjective and intercultural agreement is possible on what form morality should take. Given that we can all become better informed and more rational in our thinking, there's scope for increasing moral convergence, though no reason to think that the convergence will ever be total. Still, that leaves plenty of room for useful work to be done.
Given that we don't all value exactly the same things and don't all order our values in exactly the same way, morality is always underdetermined and contestable. Given that we value (disvalue, fear, etc.) a lot of the same things, morality and social life are possible.
The published views on all this that come closest to my own are in J.L. Mackie's Ethics: Inventing Right and Wrong. However, purely naturalistic accounts of morality, such as I've sketched, are becoming more popular. Similar ideas to Mackie's (and mine) are elaborated by, for example, Richard Joyce, Joshua Greene in his forthcoming book, Richard Garner in his superb Beyond Morality, and Richard Carrier in his underrated Sense and Goodness without God: A Defense of Metaphysical Naturalism. I have no idea why so many of these people are called "Richard". :)
Because I see no reason to reduce our values to one ubervalue, or to expect that we will ever have a fully agreed and determinate morality, I call my worked-out version of this idea "naturalistic moral pluralism" ... or just "naturalistic pluralism" for short.
I should add to the above that traditional belief systems can be barriers to rational convergence on morality (to the considerable extent that it is possible). They fossilise moral norms that are outdated and may have been pathological overreactions in the first place. Think of the extraordinary hostility that many forms of Christianity and Islam show towards sex and sexual display. Sexual desire and jealousy may be dangerous forces, but surely not that dangerous.