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

[Angrboda]

Most replies here answered some other question.

Since that doesn't appear to be true, I have to wonder why you're not seeing them. The primary answers given were a) doing good is rewarding in itself (both natively and because God has made it so [Angrboda, Mister Agenda]), and b) Natural law makes being good rewarding (because God has made us so that doing good is natural and unproblematic [Belacqua]). If I were to guess, you're looking for an answer with specific properties (it fits your preconceived ideas, it answers some previous argument, it satisfies you intellectually, etc.), none of which actually follows from the question you asked.