I never made a comment on the arbitrariness, or lack thereof, regarding religion. I merely represented the fact that the reason coupled with compassion can be cruel and arbitrary itself. Therefore, I questioned how it can be "better barometer".
Because a more meaningful and non-arbitrary set of guiding morality can be developed. One that doesn't rely on Authority without justification. Perhaps in any one instance, it will not be a better barometer. Overall though, it has the potential to be much greater.
However, religious rules are only arbitrary if they are not true. Nothing of the kind can be said for reason coupled with compassion.
There are many non-arbitrary standards one could develop such a standard by. Utilitarianism, for instance. Of course, I suppose you could claim a desire to avoid harm, or to produce the greatest good is in itself arbitrary, but given the clear preferences of billions of people and the overwhelming evidence that pain, happiness, fear and the like are all real, it basically becomes solipsism.
For instance, Christianity answered the fact that God (of the Bible) loves all mankind, therefore that question is answered.
That answers nothing. God's love has nothing to do with whether his love as a moral good or moral guide is based on his own subjective desires, or if love is good independent of God's desires.
Not all religions have gods, therefore this question would be irrelevant.
All religions offer proscriptions on behavior, and a claim as to what is moral behavior. If those religions use the supernatural as an explanation for this morality, then the question is valid. If those religions do not use the supernatural as an explanation for anything, then they probably aren't religions.
This poses an interesting question, but ultimately irrelevant to our discussion.
If god is the ultimate creator of the existence and all that it entails, and nothing exist but by it's will, then god has the right to make up such rules as he sees fit. Just like your job, you can choose not to obey the rules of the gods in terms of morallity, but then you suffer the consequences.
So certain behaviors are moral because and only because God will punish you if you do not obey? What does morality even mean in such a context? If certain Bibles are to be believed, God once commanded Abraham to kill his son in God's honor. Murder thus becomes moral because God says so? Genocide of the Canaanites becomes moral because God says so? Wholesale rape of the Canaanite women becomes moral because God says so?
If so, then all of us here are more moral than God.
This is exactly what Socrates was getting at. Arbitrary desires are one answer to the question, and not a very satisfying one.