I agree definitions vary, and that can cause confusion. For example, people unsure of what to believe can label themselves agnostic. Some call this "fence sitting". At the same time there is what's called weak atheism and strong atheism, the latter asserting there are no gods, which of course is a stupid assertion to make in an absolute sense. So weak atheism makes the most sense as it makes no assertion; it's just the absence of belief. So a weak atheist could technically be labeled agnostic, which is how I define myself, and appears the most rational definition for having no god belief.