There really should be separate words for atheism, because “a lack of belief or a strong disbelief in the existence of a god or any gods” describes two very different things.

If you think there could be a god–leaving aside for a moment the definition of what a god is–but you don’t believe in any of the popular flavors people have put forth, that’s one thing. If you believe there couldn’t possibly be any god with certitude, that’s quite something else.

For me, it’s down to definitions and possibilities. I’m not so certain of myself or what I believe that a god of a particular kind couldn’t exist, but I do believe that the pixie dust sky gods of all-you-can-eat heaven with everybody who’s ever died is a bunch of feel-good wishful thinking.