Do you not understand the meaning of the word "ultimately"?
Thank you. I assume that you're switching to solipsism now. Anything else would be disingenuous.
What better option do you have?
I'll give it a shot, morality is simply this... do justly, love mercy, and walk humbly with thy God. God in this case simply being the entirety of life... all that is, and all that you believe.
Humility wrapped in justice and mercy, if there's a higher standard for morality than this, I can't imagine what it could be. The problem as I see it, doesn't rest in finding the standard, it rests in achieving it.
Sure, but you hold that morality is sheer subjective opinion and expect that to be taken seriously.
As a solipsist I expect very little from others. You're free to follow your morals, and I'm free to follow mine. That's it... period... end of story.
However, society and its social norms are precisely what you get when you put those two simple rules into practice. You get a balance between my right to act in accordance with my morals, and your right to act in accordance with your morals.
Now this balance can fluctuate from time to time and place to place as balances are wont to do, but they'll always be adequate to the time and place in which they occur. And they'll always give their adherents the sense that they couldn't possibly be otherwise.
Morality is simply nature doing what nature always does... find a balance between two or more opposing forces such that nature, and only nature, is the true arbiter of what's moral.