The Divine Command Theory states that morality depends on what God commands to be moral and that we are morally obligated to obey God's commands. Hence, Divine Command Theory assumes morality is based on God's commands and that God will command what is morally correct.
However, one problem Divine Command Theory poses concerns motives for moral behavior, making it difficult for command theory to actually work. The theory assumes that our only motive for moral behavior would be obedience to a command. Some philosophers, like Kant, have moved past this problem by talking about a system of rewards and punishment. Kant argues that if God and an afterlife exist, then we can choose moral behavior because we'll be rewarded with eternal happiness. However, even this explanation still poses a problem as to the motives of moral behavior because if one behaves morally solely for the motive of obtaining happiness and avoiding punishment, then such behavior is definitely a "mark of moral immaturity" ("Divine Command Theory").
Another problem that Divine Command Theory raises, preventing moral demands from working, concerns the question, "Does God command this particular action because it is morally right, or is it morally right because God commands it?" ("Divine Command Theory") If one argues that an action is morally right simply because God commands it, then morality becomes arbitrary, and actions such as the Holocaust can be considered moral if we say that "God commands" them. However, if we say that God commands an action because it is morally right, then God no longer becomes the author of what is right and wrong. Instead, morality becomes something outside and above God, something that even God is driven by.
Theists try to get around the problem of arbitrary morality by asserting that God created humanity with a certain nature and would never command something that goes against that nature, such as the Holocaust. However, such a philosophy would presuppose the inherent goodness of human nature. The presupposition of mankind's inherent goodness leads to a Modified Divine Command Theory, which states that an "action is wrong if and only if it goes against the commands of a loving God." If we take being a loving God to be a necessary truth, then God becomes the author of morality because morality becomes based on God's character. If God becomes the author of morality, then morality no longer exists outside of him, and God no longer himself obeys moral laws. What's more, the conclusion can be drawn that God would never create a nature that goes against his own nature, leading to the presupposition that mankind's nature is inherently good. Hence, mankind's motive for behaving morally would be to align one's self with one's nature.
Hence, Divine Command Theory poses problems for following command because either morality becomes arbitrary or morality becomes something outside of God, commands that God himself is following as well. The way to resolve these problems is through Modified Command Theory, which asserts the inherent loving character of God and supposes that God would never command something outside of this loving character. With Modified Command Theory, the motive for following moral commands becomes simply fulfilling one's own loving nature, supposing that mankind was made in the image of God, making it possible to follow moral commands based on solid motive.