Definition: moral actions are those actions which are in keeping with the commands of God. Something is morally wrong "because God says so."
The most obvious problem with DCT is the problem of how one determines which religious tradition has it right. To "which God" and the related religious texts should I look? Allah, Yahweh, the Christian Trinity, Brahma? The Qur'an, the Torah, the Christian Bible, the Bhagavad Gita? How does one determine which "God" is the "true God?"
A second, and related problem, is that even if we can be sure that we have correctly identified the sacred text that in fact contains God's commands for moral living, we still have to properly interpret those commands. Is "jihad" morally justified or even obligatory? Muslims disagree. Are Jewish ritual food laws binding ethical requirements? Jews disagree. Is capital punishment ethical? Christians disagree. And on and on. So, even if we agree as to the sacred text that reveals God's commands, if adherents to the tradition involved do not find consensus as to what those various mandates mean, how do we know what is right and what is wrong?
However, a less obvious and more complex problem exists for DCT. The classic presentation of this topic is in Plato's Euthyphro.
Here's the question: Is something wrong simply because God says so? Or is God merely very knowledgeable of the "rules," and is thus especially able to inform us of the rules?
Let's take the latter view first. One asks, "Is lying wrong?" Answer: "Because God knows what is best for human beings, and so God knows that our lives will be better—happier, fuller, etc.—if we tell the truth." That one is pretty easy. What about this one? "Is premarital sex morally wrong?" Some would answer, "Yes, because God (in God's Word) says so. But it's not that God is just being mean or arbitrary. God knows that—even if