William Lane Craig maintains: "God's moral nature is the paradigm of goodness; what is good or bad is determined by conformity or lack thereof to His nature." Just as a live orchestra is the determinant of what constitutes "high fidelity," so God (his moral nature) is the standard for what constitutes good or bad. And since the divine one instantiates his nature by means of his divine commands, Craig reasons: "Things are right or wrong insofar as they are commanded or forbidden by God."
On the other hand, Craig believes that there can be valid reasons for divine commands. They aren't simply given willy-nilly or arbitrarily.