Sure there is more then one possible sets of morals and what sets become dominant changes. But that is not the same as moral relativism.

Different sets of morals can be better or worse acording to some metric. And such a metric can be something independent* of god, such as utilitarianism (resulting in most people to be happy or at least content). It's far from trivial, which morals really provide the best results for a given metric (even if it is to be as close as possible to gods intended morals, as there is hardly any consensus among believers, what thoose morals actually are), but you can decide on a principle.

* and i mean actually independent here, not as euphemism for atheism. There are people who believe that god's will can be expressed as "follow that philosophy", where the philosophy in question does not require god to be internally consistent. In fact i could not come up with a philosophy that would become internally inconsistent by a god ordering it.

Property? You'd have a hard time defending that as a universal principle of ethics. Indeed there are arguments to be made that ownership is fundamentally immoral.

(I'm not saying I agree with them. They aren't completely without merit, but I'm not quite ready to give up owning things just yet.)