Not your words verbatim, but saying "beginning with the position" of not having belief in a god" is essentially the same as saying "babies are born atheist".
Actually what I just said is wrong because "beginning" doesn't refer to birth as being the beginning. Your "This is the part I disagree with. While it is, as I have said, trivially true that babies are born without belief systems". As I said, "forget babies". All I'm saying is all people are atheists (don't have a god belief) before they're theists (do have a god belief).