I ran across this somewhere on the internet, but I can't find it again to credit the person for it. I thought it was very simple, yet fairly profound. Some wonder how God would solve the is-ought problem in ethics. There are several good answers to this from prominent philosophers of religion, but this one I think is pretty simple and seems so obvious.
God is omniscient, meaning He knows only and all true propositions. This would include propositions about what we ought to do. For instance, the proposition, "you ought to follow Jesus," would be known by God in light of Him being omniscient. Whether we can actually figure out why that proposition is true is separate from the fact that we can know it's true because it was stated by God.
So, we can know what we ought to do if God tells us.