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

[highdimensionman]

I was listening to William Lane Craig's moral argument. Even if we grant him that God exists and objective morality exists and god is the basis of objective morality, why do humans have moral duties? Why do we have to be good and do good other than for a selfish interest in going to heaven? He just claims that we do have moral duties (just like he claims by fiat that objective moral values exist). But why, on theism, do humans have a moral duty to be good?

Well if your too greedy without enough care it can spoil the situation for others who will move you out the way or tear jerk you into caring. Plundering to a high degree should eventually be illegal for a healthy planet which boils down to how much humanity does and doesn't care and of course what's actually achievable at that moment in time. Fact is no boogie man in the sky is going to really help you achieve a positive way forward we as people have to find our way ourselves and always keep in mind the road to hell is paved with good intention and I'm not talking about inside a volcano i'm talking like somewhere shit to live on. Theologically a limited list of outdated moral obligations are considered good to keep you in favour with god. Why something supposedly super natural would care so much about such trivial things has got to be the biggest contradiction or just the most boring dull deity bully out there.