Since there is clearly no God, even discussing the idea of an imaginary God being the author of morality is neither interesting, nor important, as the conclusion is self-evident. No God, so morality comes from self, or, at best, from a cultural agreement.
How have you drawn the conclusion there is "clearly no God?" I want to see your evidence there is clearly no God because I don't think such evidence exists. I think this is YOU trying mostly to convince yourself of your belief that no God exists. I will admit, there is no evidence for any particular perception of God over another. But clearly, something beyond the physical must exist.
Physics itself is proof of God. Here's the paradox. The very first laws of physics state that matter cannot create matter and energy can't be created or destroyed. Yet matter and energy exists. How? The physical universe cannot have created itself. It's this dichotomy that causes man to contemplate something beyond the physical.
Two problems with your statements. First, is a lack of understanding of scientific research. "There is no God" is the default null position of research. It does not require "evidence"; it is the default position. To adjust to the position of "There is a God" requires objective evidence. Thus, it is not the responsibility of anyone to "prove" there is no God. That is the given. it is the responsibility of those who claim that God exists to provide evidence of that exstence.
The second problem is that you are relying on Euclidean physics to make your claim that matter, and energy cannot be created from nothing. When you move past Euclidean physics, into quantum physics, suddenly all of those preconceptions fall away. The concept of a creator depends on a universe that has a begining, and an ending. However, the current quantum theories suggest that it has neither. There is no logical or metaphysical obstacle to completing the conventional temporal history of the universe by including an atemporal boundary condition at the beginning. Together with the successful post-Big-Bang cosmological model already in our possession, that would constitute a consistent and self-contained description of the history of the universe.
As Stephen Hawking once proposed, "So long as the universe had a beginning, we could suppose it had a creator. But if the universe is really self-contained, having no boundary or edge, it would have neither beginning nor end, it would simply be. What place, then, for a creator?"
The thing is, when we get into the realm of quantum physics, dark energy and dark matter, your "physical evidence" prerequisites for a God become even more ridiculous. Once we've opened the door of possibility to an infinite number of universes with a variable number of dimensions of space and time and they can all have their own set of physical principles and reality... then saying "clearly no god" becomes no different than looking at all the stars in the sky and saying "clearly no life"... it's just an almost preposterous impossibility.
More interesting is modern science. Quantum physics is a century old. Isn't that remarkable? It amazes me that each time Science believes we are on the brink of answering the age old questions about our origin, the more they discover things they can't explain, that completely change what we believed. Like 96% of our universe being comprised of something we can't directly relate with physically. Dark matter and dark energy.
As we approach the event horizon of a black hole, our physics principles start to break down and spiral wildly out of control. Nothing travels faster than the speed of light because time slows down and would theoretically cease. If there is no time, there can be no travel. This explains why black holes are black.
At the subatomic level, we collide atoms to see what makes them tick. Researchers at the large hadron collider (CERN) have made mind-numbing discoveries about the atom and electrons. Tiny parts of particles... things that contradict the standard model.... like particle entanglement. Electrons appearing in two places at the same time. Electrons present but not occupying any space in time. Photons are even more remarkable, seeming to have the ability to go back in time and change what they are.
So the very essence of science is being challenged today in the new sciences of quantum physics. If something like quantum physics can supersede physical sciences, why can't a God?