This paper is about the moral argument presented by William Lane Craig which claims that, without the existence of God, objective moral values and duties cannot exist. The key premise of this argument is that without the existence of God, objective moral values and duties do not exist. The second premise defends and relies on moral realism. The argument is placed in the context of metaethics, comparing theistic ethics with other metaethical theories. Apart from the objections to the argument itself, in this paper the Euthyphro dilemma is presented as a persistent challenge to the divine command theory. After the analysis of the argument, this paper continues with the exploration of naturalistic explanation of morality. The explanation of this kind is based on the theory of evolution, game theory and social contract theory. The aim of such approach is to examine whether morality can be explained by appealing to the findings of natural and social sciences and whether it can replace the theistic approach to morality by examining advantages and disadvantages of both positions.