Then an agnostic would say
Do you believe god exists? "I dont know that"
Do you believe god does not exist? "I dont know that"
There are 2 things you're mixing... (a)gnosticism and (a)theism.
Whether you believe in God or not is your (a)theistic stance.
Your (a)gnostic stance is your take on the knowledge, available or otherwise, with regard to God.
So really there are only 6 stances:
Gnostic Theist
Agnostic Theist
Gnostic Strong Atheist
Agnostic Strong Atheist
Gnostic Weak Atheist
Agnostic Weak Atheist
(BTW - Gnosticism is apparently also a separate concept to the meaning you/I are using it here:
http://en.wikipedia.org/wiki/Agnosticism - but as I think I know what you mean I will continue to use it with your understanding).
Anyhoo, the way I see it:
Gnostic Theist - Has a belief in God and has absolute knowledge of God's existence.
Agnostic Theist - Has a belief in God - but holds that absolute knowledge of God is impossible etc.
Gnostic Strong Atheist - Has belief in non-existence of God - and has absolute knowledge of his non-existence.
Agnostic Strong Atheist - Has belief in non-existence of God but holds that absolute knowledge of God is impossible etc.
Gnostic Weak Atheist - Has no belief in existence or non-existence of God - but holds that knowledge of God is possible.
Agnostic Weak Atheist - Has no belief in existence of non-existence of God - and holds that absolute knowledge of God is impossible etc.
Gnostic Theists are generally viewed as delusional - due to their inability to provide evidence to support their claims of knowledge.
Agnostic Theists are generally considered irrational - as they admit there is not the knowledge but believe anyway - maybe as a result of Pascal's Wager.
Gnostic Strong Atheists are in the same boat as Gnostic Theists - they have yet to provide evidence of non-existence - and it is usually assumed futile to try.
Agnostic Strong Atheists at least realise the lack of knowledge - yet believe - which is irrational.
Gnostic Weak Atheists is where you believe there is, or will be, sufficient evidence etc but you just can't make up your mind.
Agnostic Weak Atheist is where you don't think there is the knowledge - and thus have no belief either way. A rational position.
Which I guess is what you have stated.
So maybe it would have been easier just to say: Yes
I know I have used certain narrow definitions of Agnosticism / Gnosticism etc - but it is only to get across the distinction. A clearer understanding of Agnosticism will give you a clearer differentiation between the categories.