As Paul pointed out, it is possible to be an agnostic atheist and still have an active belief that God does not exist (or that there are no Gods, whichever way you phrase it). Agnosticism is related to knowledge alone, and the position of believing there are no Gods doesn't touch upon knowledge.
Such a position is usually called "strong" atheism, and the position of "not believing in any Gods" is "weak" atheism. It is possible to be a "strong agnostic atheist" and a "weak agnostic atheist"; the word "agnostic" allows for both. However, if you are a "gnostic atheist" (claims to know that there are no Gods), you cannot possibly be "weak", since your claim to knowledge infers a strong belief rather than a lack of belief. That is, it is impossible to know something and yet simply lack a belief in the opposite of the claim. Knowledge is a form of strong belief.
Such a position is usually called "strong" atheism, and the position of "not believing in any Gods" is "weak" atheism. It is possible to be a "strong agnostic atheist" and a "weak agnostic atheist"; the word "agnostic" allows for both. However, if you are a "gnostic atheist" (claims to know that there are no Gods), you cannot possibly be "weak", since your claim to knowledge infers a strong belief rather than a lack of belief. That is, it is impossible to know something and yet simply lack a belief in the opposite of the claim. Knowledge is a form of strong belief.
