I am not a militant atheist, but I am happy to talk.
This I disagree with. In a philosophical discussion, I define the universe as "All That Exists" (ATE). This is not the same at the STEM material universe of science. The STEM universe is part of the ATE universe. If any God or gods exist then those gods are part of the ATE universe, not separate from or outside it. By definition that ATE universe cannot have an external cause since nothing exists outside the ATE universe. If any existing component of the ATE universe is eternal, then the ATE universe is itself also eternal, and so does not require a cause.
You did well to include "with a beginning" to your concept of what God created. That leaves out a great many things. The Abrahamic God is a living God, so He did not create life. He is intelligent, so He did not create intelligence. He is jealous, angry, merciful etc. so He did not create them either. God did not create Himself, hence He did not create any of His characteristics. Those characteristics did not have a beginning, so God did not create them.
$0.02
How about we just concur that God is existence, okay?
That is the conclusion from my concept of God, namely:
"God in concept is the creator cause of man and the universe and everything with a beginning."
I am not into the God of religion, but the God of reason.
Still the God of reason is mentioned in the Bible, from this very first text in the Bible:
"In the beginning God made heaven and earth..."
And the God of religion is also and predominantly in the Bible, which is into things like hell.
So, I could add the word hell to the first text of the Bible, in order to show that the God of religion is predominantly in the Bible:
"In the beginning God made heaven and earth and hell..."
Please, everyone, just abstain from bringing in this thread the God of religion, also ideas in the Bible that are into the God of religion.
And who are going to decide what things belong to the God of religion folks, and what things belong to the God of reason folks?
Who else but us humans, do you know of some other live entities interested in God at all?