Euthypro’s argument boils down to “Is what is moral commanded by God because it is moral, or is it moral because it is commanded by God?”.

A chief difficulty in the argument is that it seems to imply that either what is good is arbitrary since God could have decided that “killing babies for fun” was good or that goodness is defined without reference to God and therefore the explanatory power of theism over against atheism is lost.

I think there is a fundamental problem with the argument, which comes about from exporting the argument from its original surroundings of the greek pantheon of gods and applying it to the Christian God. The argument is cast in terms of God’s will, which allows the possibility that everything is arbitrary, a matter of his personal fancy (notice how God’s will is seen in anthropomorphic terms, just as would have been appropriate for describing the petty squabbles of the greek gods).

However the Bible says that God is good that he is light, etc. In other words moral good is an expression of the nature and hence character of God not an arbitrary decision. The bible says that out of the character of our hearts the mouth speaks. Our actions and decisions proceed from who we are. God’s will likewise proceeds from his nature.

The original argument fails since it assumes that the will is the fundamental basis for all God’s moral law when actually it is a reflection of his nature. The moral good as with everything else can have no independent existence of God.It exists as a part of his nature.

Even if we grant that moral reasoning is a product of evolution—that still doesn’t let the athiest off the hook.  There is still the question of ultimate explanation—that is, why should the universe exist in such a way that we have come to desire “goodness”, healty, nuturing and meaningful relationships based on honest, integrity, courage, love—that we desire belonging.
We all universially recognize these laws (so to speak) of successful human interpersonal relationships that transcend culture.
What kind of “ultimate explaination” best FITS these features of our human existence?  I find it very difficult to see how this can fit an athiestic, non-personal, purely naturalistic explaination.

Good reason to believe. To present the often used analogy, if we compare Mother Theresa and Hitler, it is obvious which one is the most morally and ethically correct individual. However, if we remove divine authority, (the precise method of the evoluton of ethics, evolution of a moral code, ect, is not important) on what grounds do we say that the actions of the later were any worse than the actions of the former? We could judge on general consensus of opinion, but, if we judge something to be un/ethical based on the percentage of the population that agree with it, atheism is unethical as most of the population are theist.

Ethics as described and exemplified in the biblical writings can be put forth as a good example (if we refute or ignore their supposed divine inspiration) of humans striving to create a code for most people to live by, as worked out by trial and error over many millenia - it is not necessary to have these rules attributed to a divine authority.

Very interesting and a good starter for absolute morality. I am very interested to hear what you think of the Euthyphro argument.