I don't think atheism makes the same leap of faith. The proposition, 'God exists' is vastly different to the proposition 'God does not exist', because the former can be proven while the latter cannot. Atheists do not need to disprove god's existence, the burden of proof is on the believer.
With agnosticism, the possible existence of an infinite number of other entities such as Zeus, the Flying Mi Goreng, or the Great Green Arkleseizure must be considered. It essentially says nothing about everything.
On the other hand, atheism is step zero. It is the state from which all existence proofs begin. If all existence proofs have failed to convince you then I think it is reasonable to say that you therefore lack belief.