Massimo Pigliucci argues that atheism is philosophical, not scientific. Jerry Coyne differs:
I’ll call “weak sense atheism” the position that, I think, most atheists hold. It is this: “There is no convincing evidence for God, so I withhold belief.”...Now I don’t know anyone who is a strong-sense atheist. Even Dawkins, as I recall, is a “70% probability” man he thinks it pretty improbable that God exists, but adds that he can’t disprove the existence of some kinds of gods. I’m pretty much on board with him. You’d be a fool to say that you know absolutely that there is no being up there at all, including one that doesn’t interfere in the workings of the universe.
So let’s take weak-sense atheism (WSA) as the default stance. In its very weakest, “no-evidence-for-God” sense, WSA is absolutely scientific. After all, what is science but the claim that one needs empirical evidence before accepting something as a reality? When one says, “I see no evidence for a god, and therefore refuse to accept his/her/its reality,” one is saying nothing different from, “I see no evidence for the view that plants have feelings, and therefore I don’t accept the idea that they do.”