There is a crucial difference among those who are atheists, and I've never seen a poll.
Wikipedia gives the following definitions.
Positive atheism (also called strong atheism and hard atheism) is the form of atheism that asserts that no deities exist.
Negative atheism (also called weak atheism and soft atheism) is any other type of atheism, wherein a person does not believe in the existence of any deities, but does not explicitly assert there to be none.
Rational Wiki notes an additional type, apatheism, who has no interest in accepting or denying claims that a god or gods exist or do not exist.
So what type of atheist are you?