I'll be honest, I had trouble reading your post. Did you cut and paste this from somewhere? It's formatted oddly.
We say "almost certainly" to remain logically consistent. We can't say for certain there exists no God like was can say for certain there exists humankind because it is a logical fallacy to declare something does not exist. There's no way to prove this, we can only make decisions based on evidence. This shouldn't be considered a weak argument. Think of Russell's Teapot. I am almost certain it does not exist, but can never say with 100% certainty that it doesn't.
For all intents and purposes, it means there is not God, no Russell's Teapot, and no (gasp!) Flying Spaghetti Monster.
We say "almost certainly" to remain logically consistent. We can't say for certain there exists no God like was can say for certain there exists humankind because it is a logical fallacy to declare something does not exist. There's no way to prove this, we can only make decisions based on evidence. This shouldn't be considered a weak argument. Think of Russell's Teapot. I am almost certain it does not exist, but can never say with 100% certainty that it doesn't.
For all intents and purposes, it means there is not God, no Russell's Teapot, and no (gasp!) Flying Spaghetti Monster.