But I ask again, if it is simply part of His nature, you can not then qualify it as good and proclaim that as a solution. To say God's very nature is good is to refer to some outside principle. For how can we say God's very nature is good without comparing it to The Good.
From what I recall of ancient Greek philosophy, this is ancient Greek philosophy; that there is something referrred to as Beauty, which is outside anything we see, but to which we refer when saying someone or something is beautiful. So, you want to reconcile Christian morality with Greek philosophy? Good luck with that.
So, I will repeat the initial question--one which I think every true Christian should be capable of answering--is God the source of Morality? If so, how are His proclamations anything other than arbitrary? If God isn't the source of morality, then what reprecussions does this have on the Christian faith? Please answer.
Bizarre that you feel qualified to determine what a true Christian should be capable of. However, leaving that aside, Christianity does not agree that there is an external concept of Beauty (or anything else) to which God has to measure up. God does not answer to anyone or anything. If he did, then that thing would then be God; that much is obvious. If there were an outside source of Morality, that outward source would be God. There isn't.
God is not the source of our morality, but he is the benchmark by which our morality is measured, and always found wanting. In a sense what the Greeks had in theoretical form, we have in God himself. He is himself Truth, Goodness, Love, Mercy, Compassion etc. He does not have to refer to a standard outside himself, because those things are inherent to himself.
God sets the standard of morality, and we aspire to it. The repercussions for the Christian faith are that none of us will ever actually get there, because we are fallible and human, and he is not. God's morality will always be beyond our reach, but we can still try.
So, we look to Christ, we aim to emulate his standard, we use him as the benchmark for our lives. The source of our morality is his example; his life, his teachings, combined with Grace from God to allow us to follow that example. Christ is the best example we have, so we follow him. And, as I have already said, there is no society on earth capable of living by the same morality as Christ teaches; it is very much a morality of the individual before God, searching his or her heart daily for anything that would dishonour the Lord.