I often hear things.

I often hear people who claim that "morality" isn't objective.  That "right and wrong" aren't defined in the context and nature of God.   That society determines what's moral (obviously, this one makes it impossible to declare anything universally immoral.).   That we don't decide morality by "God's rules" in scripture.

The following are some excerpts from a review of Sam Harris' attempts to ground morality in an materialistic worldview.  There are some good point made here.  

"Does atheism provide a sound foundation for objective moral duties? Duty has to do with moral obligation and prohibition, what I ought or ought not to do. Here reviewers of The Moral Landscape have been merciless in pounding Harris’ attempt to provide a naturalistic account of moral obligation. Two problems stand out.
First: Natural science tells us only what is, not what ought to be, the case. As philosopher Jerry Fodor has written, “Science is about facts, not norms; it might tell us how we are, but it wouldn’t tell us what is wrong with how we are.” In particular it cannot tell us that we have a moral obligation to take actions that are conducive to human flourishing.
So if there is no God, what foundation remains for objective moral duties? On the naturalistic view, human beings are just animals, and animals have no moral obligations to one another. When a lion kills a zebra, it kills the zebra, but it does not murder the zebra. When a great white shark forcibly copulates with a female, it forcibly copulates with her but it does not rape her — for there is no moral dimension to these actions. They are neither prohibited nor obligatory.
So if God does not exist, why think we have any moral obligations to do anything? Who or what imposes these moral duties on us? Where do they come from? It is hard to see why they would be anything more than a subjective impression ingrained into us by societal and parental conditioning."

          "

Second: “ought” implies “can.” A person is not morally responsible for an action he is unable to avoid. For example, if somebody shoves you into another person, you are not to blame for bumping into this person. You had no choice. But Harris believes that all of our actions are causally determined and that there is no free will. Harris rejects not only libertarian accounts of freedom but also compatibilistic accounts of freedom. But if there is no free will, no one is morally responsible for anything. In the end, Harris admits this, though it’s tucked away in his endnotes. Moral responsibility, he says, “is a social construct,” not an objective reality: “in neuroscientific terms no person is more or less responsible than any other” for the actions they perform. His thoroughgoing determinism spells the end of any hope or possibility of objective moral duties on his worldview because we have no control over what we do.
Harris recognizes that “determinism really does threaten free will and responsibility as we intuitively understand them.” But not to worry! “The illusion of free will is itself an illusion.” The point, I take it, is that we do not really have the illusion of free will. Not only is such a claim patently false phenomenologically, as any of us can attest, but it is also irrelevant. The fact remains that whether we experience the illusion of free will or not, on Harris’ view we are thoroughly determined in all that we think and do and can therefore have no moral responsibilities."

There are plenty of problems with this worldview, but they'll most likely be ignored and misrepresented.