/// I am eager to understand the atheist mindset.///
No, you're not.
You want answers which you can dismiss or refute by posting YouTube videos by other believers....
I am an Athiest and don't have a clue how the Universe was created. And whilst it would be fascinating to know the answer, (I sincerely believe that there is *no* Intelligent Design behind it all) it doesn't keep me awake at nights.
I am not sure quite how many times you can keep asking the same question when you always dismiss any answers, thoughts or theories offered as being unacceptable (according to your very narrow parameters of 'acceptability).