Jason Rosenhouse links to this article by philosopher Mary Midgley, which asserts:

It should surely be obvious that there is nothing scientific about atheism. God’s existence is not a question for the tests of physical science; it belongs to metaphysics.

It should be obvious, huh? Well, it's not obvious to me. If a scientific mindset is a way of looking at the world, particularly by trying to understand it through a critical eye with a demand for strong evidence, then the question of the existence of anything (god, electrons, unicorns, dinosaurs) is scientific.

Whenever you ask yourself, "Do I believe in X?" how do you go about answering that question? In the case of, for example, dogs, you presumably rely on multiple observations of such organisms. I.e., you have a lot of strong, first-hand experience of dogs sufficient to justify your belief in them. When it comes to things you may not have observed first-hand, like leprechauns or Alpha Centauri, how do you go about justifying your belief either for or against them?

If you use a scientific mindset, you justify your belief (or disbelief) on the presence or absence of reliable evidence. If you reasonably trust the independent observations of thousands of astronomers who have observed Alpha Centauri by more direct means, then you will have a high confidence that it exists. But what about leprechauns? Do mythical creatures fall into the same metaphysical category Midgley is talking about above? Am I not justified in having a very low confidence that leprechauns exist because there is very little evidence for them?

That just seems silly, doesn't it? Is the question of the existence of leprechauns a scientific question, or a metaphysical one? And why would the question of the existence of god necessarily fall into that category too?

A scientific mindset proceeds from skepticism. You assume that something doesn't exist until you have good evidence to the contrary. The alternative is to accept the existence of things unseen without good evidence. This is called "faith".

Most people actually tend to employ both kinds of thinking when deciding what to believe in. The vast majority of everyday interaction proceeds on the basis of beliefs derived empirically. But then, most people in the world are also religious, and so they use a different set of criteria for determining belief in the supernatural.

But Midgley's just flat-out wrong to say there's nothing scientific about the question of the existence of god. The most scientific thing in the world is to start from scratch and work your way up through careful consideration of the evidence, while believing in god requires a very big, initial, unfounded leap.