Lookie

Will Wilkinson---responding to a Eugene Volokh vamp on the standard bebop head "aren't scientists who claim evolution without God is the process by which biological speciation occurred merely asserting their own faith without proof?"---makes a specific statement of the best general case against being a theist. And that is: there is no neutral position midway between equally faith-based beliefs in God and beliefs in scientific naturalism. Will, invoking Quine (who was really just restating Occam's Razor), notes that:

The best explanatory theory of the emergence of life and the development of biological variety is the theory of evolution by natural selection. The statement of this theory does not require us to quantify over, or commit to, any supernatural properties. That "God had no part in the process" is straightforwardly implied by the fact that the theory does not mention God or God-properties. The "proof" that God is no part of the process is simply the statement of the theory, and the fact that the theory is the best, whatever our criteria for "best" are. You can tell that something has no part in the process by checking the list of things one is ontologically committed to by dint of accepting the theory. If it isn't on the list, it plays no part.

In other words, in the construction of an ontological theory, there aren't three positions 1, 0, and -1 on the existence of any x such that it's proper to believe 0(x) until evidence comes in. There are only two positions, 1 and 0, and one doesn't add x to the list of things in whose existence one believes without x being an irreducible component of the explanatory theory of one's observed phenomena. If, as the saying goes, God "does no work" in any of the (biological, chemical, physical) theories by which we explain the universe, God doesn't make it into our ontology. That's not an assertion of faith, it's an assertion of scientific skepticism. And Will's right: the Volokhian take is a way of flirting with Meinong's realms of existence and schmexistence.