Does an Uncaused Universe Prove Atheism?

Suppose Quentin Smith succeeds in demonstrating that the actual universe began to exist without being caused to exist. Does this entail atheism?

An easy counter-example: there exists a theistic God, who did not cause the unviverse, and yet the universe began to exist.

The inability of a Quentonian argument to constitute positive proof of atheism does not prove theism, it just undercuts the potency of such an atheistic argument. If his argument is successful however, it will undercut all cosmological arguments, decreasing the reasons that some theists have for believing that God exists.

The difficulty in positively proving atheism is cited by some atheists as a point of persuasion, as if to say, "sure, my argument does not logically entail atheism proper, but no argument can, so give me a break". I have not been persuaded that it is necessarily the case that no argument can prove atheism, or theism for that matter. This is a point whose converse I am willing to grant for the sake of argument however.

My main point? Arguments that undercut theistic arguments do not entail atheism and vice versa.

My question to you: what types of enterprises seem likely candidates to succesfully provide positive evidence for atheism?