Why Agnosticism?

[Ace Otana]

Your argument regarding babies does not count. This is because babies are not aware of the concept of God.

It doesn't matter if you're aware of the claim or not. If you lack belief in god, then you lack belief in it. Simple.
When I became aware of the god claim, I remained unconvinced. So is this where I took that leap of faith for which I wasn't aware of?
Remember, I'm not claiming anything. The burden of proof is not on me. Theists make a claim, I as an atheist reject that claim due to lack of evidence and credibility. No faith involved.

since there is a clear difference between a concept that billions of people claim exists and one in which nobody would assert.

Numbers count for nothing when it comes to what's real or not. This is nothing but a populum argument, for which does not work.
A lie is a lie even if everyone believed it, a truth is a truth even if no one believed it.
Numbers count for nothing. God is no more supported or credible than any other imaginary being you can think of. Until you can give us real reasons as to why god should be more considered than any other imaginary character, god is nothing but a joke like everything else.

but, if you do not have this knowledge, then you are making a judgement which is based upon incomplete knowledge which absolutely requires belief.

No. I am making judgement based on evidence and credibility. For which theist claims lack both. Knowledge does not need to be complete to make judgement of what you know now at this point in time. If evidence were to be found for a god, then reconsideration will take place. But until then, it will remain rejected due to lack of evidence and/or credibility.

and therefore you form the belief that He doesn't.

No. Theists make the claim that a god exists. They believe in this god thing, I do not. It takes faith to believe in something without anything to support it. I lack belief.
Here is another way of putting it, I with-hold judgement on the existence of god. Lack of belief is a default position, we all start off with this position. I'll continue to with-hold judgement until I see good reason to believe in this god.

Question: Do you believe in god or not?

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Atheism is in it's most basic sense, lack of belief in god or gods. Nothing more, nothing less. No faith required. You don't need faith to lack belief in anything. If it takes faith to lack belief in god, then it takes faith to lack belief in ANYTHING!
You are demanding special treatment a little. Otherwise known as 'special pleading'