On theism, why do humans have moral duties even if there are objective moral values?

[Pnerd]

My point was not to pass a value judgement on self-interest. I was asking whether there are reasons other than self-interest for believing (from a theistic perspective) that humans have moral duties and obligations towards others.
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As I keep trying to explain......the bold indicates that your question is malformed.  

Asserting objective moral duties and obligations towards others can only be done one way, which has nothing to do with gods or god beliefs...at all.  A theist is as free to assert (or reject) such duties and obligations as an atheist.  Are you unclear as to why a person would believe as much?  Can you personally think of any reason why we would have moral duties and obligations towards others that satisfy the criteria of objectivity?  

Of course, I can. My reasons are non-theistic reasons. But as I mentioned in my first post, my reason for asking the question was William Lane Craig's claims regarding his moral argument. He claims that humans have moral duties and obligations. He also claims that from an atheistic viewpoint, there is no way to have objective moral values. That got me wondering why a theist like Craig might think humans have moral duties from his theistic perspective which is not available to an atheist. If a theist's view on moral duties is no different from an atheist's, then Craig's claim (that objective morality is possible only from a theistic perspective) is wrong, which was my point. Surely, someone with Craig's beliefs doesn't believe that the motivation for behaving morally is the same for a theist and an atheist. I'm wondering where a theist like Craig believes his moral obligations come from.