Faced with the fundamental question: "Why is there something rather than nothing?" atheists have faith that science will tell us eventually. Most seem never to consider that it may well be a philosophic, logical impossibility for something to create itself from nothing. But the question presents a fundamental mystery that has bedeviled (so to speak) philosophers and theologians from Aristotle to Aquinas. Recently scientists have tried to answer it with theories of "multiverses" and "vacuums filled with quantum potentialities," none of which strikes me as persuasive. (For a review of the centrality, and insolubility so far, of the something-from-nothing question, I recommend this podcast interview with Jim Holt, who is writing a book on the subject.)Oh, well, okay, they don't strike you as convincing. Oh, that settles it.
The question "why is there something rather than nothing" is evidently meant to invoke some kind of profound ontological and epistemological conundrum, but it is in fact mere fallacy masquerading as philosophy. Define something. Define nothing. Define rather than. Let me propose to you that nothingness as universal (uh, multiversal?) nonexistence is less than meaningless even if only meant as a glib converse to "all this shit, you know, like life and planets and stars and galaxies and stuff." It is the most elementary Aristotlean canard of the prime mover dressed up for an era with fancier mathematics. Ron Rosenbaum, you are regular-old ∞ in an א world.
While some atheists may evince confidence that scientific inquiry may one day explain the mechanisms through which reality came to existence or existence became real or what have you, atheism such as it is makes no claims about the matter. Atheism encompasses a single proposition: there is no deity or deities.
Now. Insofar as science has explained natural phenomena, it is a useful tool and method. Most atheists would agree. However, science has no opinion on the fundamental nature of being or the meaning of life. The scientific method is a means of inquiry, a system for developing descriptive, prescriptive, and predictive models of natural systems, not a means of answering all the questions that occur to you when you get stoned. Eat some fucking Doritos and chill the fuck out.
Agnosticism accords a weird respect to a plainly untrue proposition: that there is either a single supernatural entity or a pantheon of supernatural entities who somehow brought the universe into existence and, furthermore, continue to affect its workings, in particular, who take an actual and active interests in the goings-on of Homo sapiens. These supernatural entitities are either easily discounted and disproved (the God/s of Western "mono"theism) or else construed in such an attribute-less, indefinable, vague, and incoherent manner as to be fundamentally nonexistent anyway--indeed, it has become the bread-and-butter of the, uh, "new theists," to define god so broadly as to un-define him.
Personally, I do not think that human science will ever adequately account for the existence of existence, because I think that the question itself contains a category error. Nothing about this conviction of the limits of human knowledge implies the existence of divinity.