I didn't say it was new. I said it generally isn't read that way. Which it isn't. Earliest beliefs are considered to have been monotheistic. Much later giving way to many Gods, eventually returning to the one God idea again for mainstream contemporary religions, putting the imaginary God concept as creator above everything including Nature. God=Nature is not the way a vast majority of religious belief has ever gone as far as I'm aware. I don't know what you mean by "(sub)set". Broadly speaking I think we agree, what is moral and morality itself are those standards which promote well being and do least harm possible and least necessary to people and things. In my view, standards encapsulated into law by a free and democratic society openly voting its lawmakers into and out of office, is a moral procedure which allows morality to evolve to the highest definition. Morality does not belong to, nor is it the preserve of any "(sub)set" of humans. That would be less than moral. Perhaps you don't mean that. It's true the majority in any free society put what they consider to be moral standards into effect, so I suppose that leaves a subset that might not agree but who in the long run might be found to be right. However Relative morality quite rightly (and therefore morally), does rationally render reliance on "(sub)set" God as less than moral to say the least, whether or not God=Nature. However you've dropped any mention of God as a "(sub)set" being required or necessary, which was my point. If that's what you're saying then I agree with you that far. I think we can still also agree morality is relative and cannot be the idealistically absolute some like to claim it is.
In The Theory of Moral Sentiments, Adam Smith considers morals to be a matter of emotion. Eminent philosophers of the time successfully argued that was not so, particularly Thomas Reid in his ..Principles of Common Sense., which determines how morals are rather - ascertained.