Morality entails a moral obligation outside of ourselves. We certainly find that there are moral rules that we are obliged to follow. Everyone is aware of this and this is why we all complain about people who break them. We are aware of their existence and their incumbency on us. If you have a creature that has a mechanism built into them that makes them aware of these moral rules, then the rules and the mechanism are made for each other. That kind of fit would suggest a fitter behind that. In addition, if you have moral laws, then you have to have a moral law maker that has the authority to enforce those laws and to whom we are obliged to answer for breaking them, therefore the incumbency. God explains or grounds the existence of morality. Empathy does not come with any moral incumbency. There was plenty of empathy directed toward the Nazis in Germany, but empathy is not inherently morally good as my example shows. So, you cannot ground morality in that, but God is inherently good and thus we can ground morality in the morally Good nature of God.