Atheism is defined by the belief in gods as much theism is.
You're not talking about implicit atheism...
If you are going to start a thread about the default position, you have to address the type of atheism that the default position would adhere to.
All of your arguments thus far are about either strong or weak atheism - which obviously are not the default position.
Implicit and explicit atheism - Wikipedia, the free encyclopedia
How can an empty mind hold a concept of 'lack of belief'?
Does a empty coke can hold no coke?
Does an empty chair hold no buttocks?
Does an empty car hold no driver?
An empty mind can likewise hold no belief.
What does 'Without a belief' mean? Belief needs a subject here, for example, a particular deity. To say "I lack a belief in the particular deity" you must hold a concept of the particular deity in your mind.
It means to not have a belief...
If you want to add particular deities to the mix, then you're no longer talking about implicit atheism. Once you mention a deity, as I did with Abe-Mango, you've moved on from the realm of implicit atheism and immediately have to decide whether or not you are going to actively believe or disbelieve in said deity. Once you've started this part of the conversation, you're no longer talking about implicit atheism.
So, the question whether baby has belief of a deity is meaningless.
It's not meaningless - it's simply a fact. Just as your stone example - babies are implicitly atheists - just as you were towards Abe-Mango.
You're now, however, either a weak atheist or strong atheist towards Abe-Mango. Either way, you're an atheist.
Agree. But why atheists abandon that position?
I'm one of the few who doesn't. I have left behind my implicit and weak atheism and openly say that there are no gods, and that gods are merely figments of well-intentioned imaginations.